diff --git a/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/EntityChangeEventHelper.cs b/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/EntityChangeEventHelper.cs
index e3a0a9a050..9f4fe25fcf 100644
--- a/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/EntityChangeEventHelper.cs
+++ b/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/EntityChangeEventHelper.cs
@@ -23,98 +23,86 @@ namespace Volo.Abp.Domain.Entities.Events
             EventBus = NullEventBus.Instance;
         }
 
-        public virtual void TriggerEvents(EntityChangeReport changeReport)
+        public async Task TriggerEventsAsync(EntityChangeReport changeReport)
         {
-            TriggerEventsInternal(changeReport);
+            await TriggerEventsInternalAsync(changeReport);
 
             if (changeReport.IsEmpty() || _unitOfWorkManager.Current == null)
             {
                 return;
             }
 
-            _unitOfWorkManager.Current.SaveChanges();
+            await _unitOfWorkManager.Current.SaveChangesAsync();
         }
 
-        public Task TriggerEventsAsync(EntityChangeReport changeReport) //TODO: Trigger events really async!
+        public virtual async Task TriggerEntityCreatingEventAsync(object entity)
         {
-            TriggerEventsInternal(changeReport);
-
-            if (changeReport.IsEmpty() || _unitOfWorkManager.Current == null)
-            {
-                return Task.FromResult(0);
-            }
-
-            return _unitOfWorkManager.Current.SaveChangesAsync();
-        }
-
-        public virtual void TriggerEntityCreatingEvent(object entity)
-        {
-            TriggerEventWithEntity(typeof(EntityCreatingEventData<>), entity, true);
+            await TriggerEventWithEntity(typeof(EntityCreatingEventData<>), entity, true);
         }
 
-        public void TriggerEntityCreatedEvent(object entity)
+        public async Task TriggerEntityCreatedEventAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityCreatedEventData<>), entity, true);
+            await TriggerEventWithEntity(typeof(EntityCreatedEventData<>), entity, true);
         }
 
-        public virtual void TriggerEntityCreatedEventOnUowCompleted(object entity)
+        public virtual async Task TriggerEntityCreatedEventOnUowCompletedAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityCreatedEventData<>), entity, false);
+            await TriggerEventWithEntity(typeof(EntityCreatedEventData<>), entity, false);
         }
 
-        public virtual void TriggerEntityUpdatingEvent(object entity)
+        public virtual async Task TriggerEntityUpdatingEventAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityUpdatingEventData<>), entity, true);
+            await TriggerEventWithEntity(typeof(EntityUpdatingEventData<>), entity, true);
         }
 
-        public void TriggerEntityUpdatedEvent(object entity)
+        public async Task TriggerEntityUpdatedEventAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityUpdatedEventData<>), entity, true);
+            await TriggerEventWithEntity(typeof(EntityUpdatedEventData<>), entity, true);
         }
 
-        public virtual void TriggerEntityUpdatedEventOnUowCompleted(object entity)
+        public virtual async Task TriggerEntityUpdatedEventOnUowCompletedAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityUpdatedEventData<>), entity, false);
+            await TriggerEventWithEntity(typeof(EntityUpdatedEventData<>), entity, false);
         }
 
-        public virtual void TriggerEntityDeletingEvent(object entity)
+        public virtual async Task TriggerEntityDeletingEventAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityDeletingEventData<>), entity, true);
+            await TriggerEventWithEntity(typeof(EntityDeletingEventData<>), entity, true);
         }
 
-        public void TriggerEntityDeletedEvent(object entity)
+        public async Task TriggerEntityDeletedEventAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityDeletedEventData<>), entity, true);
+            await TriggerEventWithEntity(typeof(EntityDeletedEventData<>), entity, true);
         }
 
-        public virtual void TriggerEntityDeletedEventOnUowCompleted(object entity)
+        public virtual async Task TriggerEntityDeletedEventOnUowCompletedAsync(object entity)
         {
-            TriggerEventWithEntity(typeof(EntityDeletedEventData<>), entity, false);
+            await TriggerEventWithEntity(typeof(EntityDeletedEventData<>), entity, false);
         }
 
-        public virtual void TriggerEventsInternal(EntityChangeReport changeReport)
+        protected virtual async Task TriggerEventsInternalAsync(EntityChangeReport changeReport)
         {
-            TriggerEntityChangeEvents(changeReport.ChangedEntities);
-            TriggerDomainEvents(changeReport.DomainEvents);
+            await TriggerEntityChangeEvents(changeReport.ChangedEntities);
+            await TriggerDomainEvents(changeReport.DomainEvents);
         }
 
-        protected virtual void TriggerEntityChangeEvents(List<EntityChangeEntry> changedEntities)
+        protected virtual async Task TriggerEntityChangeEvents(List<EntityChangeEntry> changedEntities)
         {
             foreach (var changedEntity in changedEntities)
             {
                 switch (changedEntity.ChangeType)
                 {
                     case EntityChangeType.Created:
-                        TriggerEntityCreatingEvent(changedEntity.Entity);
-                        TriggerEntityCreatedEventOnUowCompleted(changedEntity.Entity);
+                        await TriggerEntityCreatingEventAsync(changedEntity.Entity);
+                        await TriggerEntityCreatedEventOnUowCompletedAsync(changedEntity.Entity);
                         break;
                     case EntityChangeType.Updated:
-                        TriggerEntityUpdatingEvent(changedEntity.Entity);
-                        TriggerEntityUpdatedEventOnUowCompleted(changedEntity.Entity);
+                        await TriggerEntityUpdatingEventAsync(changedEntity.Entity);
+                        await TriggerEntityUpdatedEventOnUowCompletedAsync(changedEntity.Entity);
                         break;
                     case EntityChangeType.Deleted:
-                        TriggerEntityDeletingEvent(changedEntity.Entity);
-                        TriggerEntityDeletedEventOnUowCompleted(changedEntity.Entity);
+                        await TriggerEntityDeletingEventAsync(changedEntity.Entity);
+                        await TriggerEntityDeletedEventOnUowCompletedAsync(changedEntity.Entity);
                         break;
                     default:
                         throw new AbpException("Unknown EntityChangeType: " + changedEntity.ChangeType);
@@ -122,26 +110,26 @@ namespace Volo.Abp.Domain.Entities.Events
             }
         }
 
-        protected virtual void TriggerDomainEvents(List<DomainEventEntry> domainEvents)
+        protected virtual async Task TriggerDomainEvents(List<DomainEventEntry> domainEvents)
         {
             foreach (var domainEvent in domainEvents)
             {
-                EventBus.Trigger(domainEvent.EventData.GetType(), domainEvent.EventData);
+                await EventBus.TriggerAsync(domainEvent.EventData.GetType(), domainEvent.EventData);
             }
         }
 
-        protected virtual void TriggerEventWithEntity(Type genericEventType, object entity, bool triggerInCurrentUnitOfWork)
+        protected virtual async Task TriggerEventWithEntity(Type genericEventType, object entity, bool triggerInCurrentUnitOfWork)
         {
             var entityType = ProxyHelper.UnProxy(entity).GetType();
             var eventType = genericEventType.MakeGenericType(entityType);
 
             if (triggerInCurrentUnitOfWork || _unitOfWorkManager.Current == null)
             {
-                EventBus.Trigger(eventType, Activator.CreateInstance(eventType, entity));
+                await EventBus.TriggerAsync(eventType, Activator.CreateInstance(eventType, entity));
                 return;
             }
 
-            _unitOfWorkManager.Current.Completed += (sender, args) => EventBus.Trigger(eventType, Activator.CreateInstance(eventType, entity));
+            _unitOfWorkManager.Current.OnCompleted(() => EventBus.TriggerAsync(eventType, Activator.CreateInstance(eventType, entity)));
         }
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/IEntityChangeEventHelper.cs b/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/IEntityChangeEventHelper.cs
index bcd6f782b9..acfcfb9875 100644
--- a/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/IEntityChangeEventHelper.cs
+++ b/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/IEntityChangeEventHelper.cs
@@ -7,26 +7,18 @@ namespace Volo.Abp.Domain.Entities.Events
     /// </summary>
     public interface IEntityChangeEventHelper
     {
-        void TriggerEvents(EntityChangeReport changeReport);
-
         Task TriggerEventsAsync(EntityChangeReport changeReport);
 
-        void TriggerEntityCreatingEvent(object entity);
-
-        void TriggerEntityCreatedEvent(object entity);
-
-        void TriggerEntityCreatedEventOnUowCompleted(object entity);
-
-        void TriggerEntityUpdatingEvent(object entity);
-
-        void TriggerEntityUpdatedEvent(object entity);
-
-        void TriggerEntityUpdatedEventOnUowCompleted(object entity);
+        Task TriggerEntityCreatingEventAsync(object entity);
+        Task TriggerEntityCreatedEventAsync(object entity);
+        Task TriggerEntityCreatedEventOnUowCompletedAsync(object entity);
 
-        void TriggerEntityDeletingEvent(object entity);
+        Task TriggerEntityUpdatingEventAsync(object entity);
+        Task TriggerEntityUpdatedEventAsync(object entity);
+        Task TriggerEntityUpdatedEventOnUowCompletedAsync(object entity);
 
-        void TriggerEntityDeletedEvent(object entity);
-        
-        void TriggerEntityDeletedEventOnUowCompleted(object entity);
+        Task TriggerEntityDeletingEventAsync(object entity);
+        Task TriggerEntityDeletedEventAsync(object entity);
+        Task TriggerEntityDeletedEventOnUowCompletedAsync(object entity);
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/NullEntityChangeEventHelper.cs b/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/NullEntityChangeEventHelper.cs
index c6f8a7afa4..85b660ed08 100644
--- a/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/NullEntityChangeEventHelper.cs
+++ b/src/Volo.Abp.Ddd.Domain/Volo/Abp/Domain/Entities/Events/NullEntityChangeEventHelper.cs
@@ -17,54 +17,49 @@ namespace Volo.Abp.Domain.Entities.Events
 
         }
 
-        public void TriggerEntityCreatingEvent(object entity)
+        public Task TriggerEntityCreatingEventAsync(object entity)
         {
-            
-        }
-
-        public void TriggerEntityCreatedEvent(object entity)
-        {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityCreatedEventOnUowCompleted(object entity)
+        public Task TriggerEntityCreatedEventAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityUpdatingEvent(object entity)
+        public Task TriggerEntityCreatedEventOnUowCompletedAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityUpdatedEvent(object entity)
+        public Task TriggerEntityUpdatingEventAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityUpdatedEventOnUowCompleted(object entity)
+        public Task TriggerEntityUpdatedEventAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityDeletingEvent(object entity)
+        public Task TriggerEntityUpdatedEventOnUowCompletedAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityDeletedEvent(object entity)
+        public Task TriggerEntityDeletingEventAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEntityDeletedEventOnUowCompleted(object entity)
+        public Task TriggerEntityDeletedEventAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
-        public void TriggerEvents(EntityChangeReport changeReport)
+        public Task TriggerEntityDeletedEventOnUowCompletedAsync(object entity)
         {
-            
+            return Task.CompletedTask;
         }
 
         public Task TriggerEventsAsync(EntityChangeReport changeReport)
diff --git a/src/Volo.Abp.EntityFrameworkCore/Volo/Abp/EntityFrameworkCore/AbpDbContext.cs b/src/Volo.Abp.EntityFrameworkCore/Volo/Abp/EntityFrameworkCore/AbpDbContext.cs
index 5c4281d5f1..e5cbfcae66 100644
--- a/src/Volo.Abp.EntityFrameworkCore/Volo/Abp/EntityFrameworkCore/AbpDbContext.cs
+++ b/src/Volo.Abp.EntityFrameworkCore/Volo/Abp/EntityFrameworkCore/AbpDbContext.cs
@@ -17,6 +17,7 @@ using Volo.Abp.Domain.Entities.Events;
 using Volo.Abp.Guids;
 using Volo.Abp.MultiTenancy;
 using Volo.Abp.Reflection;
+using Volo.Abp.Threading;
 
 namespace Volo.Abp.EntityFrameworkCore
 {
@@ -76,7 +77,7 @@ namespace Volo.Abp.EntityFrameworkCore
                 ChangeTracker.AutoDetectChangesEnabled = false; //TODO: Why this is needed?
                 var changeReport = ApplyAbpConcepts();
                 var result = base.SaveChanges(acceptAllChangesOnSuccess);
-                EntityChangeEventHelper.TriggerEvents(changeReport);
+                AsyncHelper.RunSync(() => EntityChangeEventHelper.TriggerEventsAsync(changeReport));
                 return result;
             }
             catch (DbUpdateConcurrencyException ex)
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/ActionEventHandler.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/ActionEventHandler.cs
index e5b6767770..32b41ec800 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/ActionEventHandler.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/ActionEventHandler.cs
@@ -1,10 +1,11 @@
 using System;
+using System.Threading.Tasks;
 using Volo.Abp.DependencyInjection;
 
 namespace Volo.Abp.EventBus
 {
     /// <summary>
-    /// This event handler is an adapter to be able to use an action as <see cref="IEventHandler{TEventData}"/> implementation.
+    /// This event handler is an adapter to be able to use an action as <see cref="IEventHandler{TEvent}"/> implementation.
     /// </summary>
     /// <typeparam name="TEvent">Event type</typeparam>
     internal class ActionEventHandler<TEvent> :
@@ -12,15 +13,15 @@ namespace Volo.Abp.EventBus
         ITransientDependency
     {
         /// <summary>
-        /// Action to handle the event.
+        /// Function to handle the event.
         /// </summary>
-        public Action<TEvent> Action { get; private set; }
+        public Func<TEvent, Task> Action { get; }
 
         /// <summary>
-        /// Creates a new instance of <see cref="ActionEventHandler{TEventData}"/>.
+        /// Creates a new instance of <see cref="ActionEventHandler{TEvent}"/>.
         /// </summary>
         /// <param name="handler">Action to handle the event</param>
-        public ActionEventHandler(Action<TEvent> handler)
+        public ActionEventHandler(Func<TEvent, Task> handler)
         {
             Action = handler;
         }
@@ -29,9 +30,9 @@ namespace Volo.Abp.EventBus
         /// Handles the event.
         /// </summary>
         /// <param name="eventData"></param>
-        public void HandleEvent(TEvent eventData)
+        public async Task HandleEventAsync(TEvent eventData)
         {
-            Action(eventData);
+            await Action(eventData);
         }
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/AsyncActionEventHandler.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/AsyncActionEventHandler.cs
deleted file mode 100644
index fb566f8775..0000000000
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/AsyncActionEventHandler.cs
+++ /dev/null
@@ -1,38 +0,0 @@
-using System;
-using System.Threading.Tasks;
-using Volo.Abp.DependencyInjection;
-
-namespace Volo.Abp.EventBus
-{
-    /// <summary>
-    /// This event handler is an adapter to be able to use an action as <see cref="IAsyncEventHandler{TEventData}"/> implementation.
-    /// </summary>
-    /// <typeparam name="TEvent">Event type</typeparam>
-    internal class AsyncActionEventHandler<TEvent> :
-        IAsyncEventHandler<TEvent>,
-        ITransientDependency
-    {
-        /// <summary>
-        /// Function to handle the event.
-        /// </summary>
-        public Func<TEvent, Task> Action { get; }
-
-        /// <summary>
-        /// Creates a new instance of <see cref="AsyncActionEventHandler{TEventData}"/>.
-        /// </summary>
-        /// <param name="handler">Action to handle the event</param>
-        public AsyncActionEventHandler(Func<TEvent, Task> handler)
-        {
-            Action = handler;
-        }
-
-        /// <summary>
-        /// Handles the event.
-        /// </summary>
-        /// <param name="eventData"></param>
-        public async Task HandleEventAsync(TEvent eventData)
-        {
-            await Action(eventData);
-        }
-    }
-}
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/EventBus.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/EventBus.cs
index f0a10c678f..8b4fdf345b 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/EventBus.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/EventBus.cs
@@ -64,30 +64,17 @@ namespace Volo.Abp.EventBus
         }
 
         /// <inheritdoc/>
-        public IDisposable Register<TEvent>(Action<TEvent> action)
-            where TEvent : class
+        public IDisposable Register<TEvent>(Func<TEvent, Task> action) where TEvent : class
         {
             return Register(typeof(TEvent), new ActionEventHandler<TEvent>(action));
         }
 
-        /// <inheritdoc/>
-        public IDisposable AsyncRegister<TEvent>(Func<TEvent, Task> action) where TEvent : class
-        {
-            return Register(typeof(TEvent), new AsyncActionEventHandler<TEvent>(action));
-        }
-
         /// <inheritdoc/>
         public IDisposable Register<TEvent>(IEventHandler<TEvent> handler) where TEvent : class
         {
             return Register(typeof(TEvent), handler);
         }
 
-        /// <inheritdoc/>
-        public IDisposable AsyncRegister<TEvent>(IAsyncEventHandler<TEvent> handler) where TEvent : class
-        {
-            return Register(typeof(TEvent), handler);
-        }
-
         /// <inheritdoc/>
         public IDisposable Register<TEvent, THandler>()
             where TEvent : class
@@ -117,34 +104,6 @@ namespace Volo.Abp.EventBus
             return new EventHandlerFactoryUnregistrar(this, eventType, factory);
         }
 
-        /// <inheritdoc/>
-        public void Unregister<TEvent>(Action<TEvent> action) where TEvent : class
-        {
-            Check.NotNull(action, nameof(action));
-
-            GetOrCreateHandlerFactories(typeof(TEvent))
-                .Locking(factories =>
-                {
-                    factories.RemoveAll(
-                        factory =>
-                        {
-                            var singleInstanceFactory = factory as SingleInstanceHandlerFactory;
-                            if (singleInstanceFactory == null)
-                            {
-                                return false;
-                            }
-
-                            var actionHandler = singleInstanceFactory.HandlerInstance as ActionEventHandler<TEvent>;
-                            if (actionHandler == null)
-                            {
-                                return false;
-                            }
-
-                            return actionHandler.Action == action;
-                        });
-                });
-        }
-
         /// <inheritdoc/>
         public void AsyncUnregister<TEvent>(Func<TEvent, Task> action) where TEvent : class
         {
@@ -162,7 +121,7 @@ namespace Volo.Abp.EventBus
                                 return false;
                             }
 
-                            var actionHandler = singleInstanceFactory.HandlerInstance as AsyncActionEventHandler<TEvent>;
+                            var actionHandler = singleInstanceFactory.HandlerInstance as ActionEventHandler<TEvent>;
                             if (actionHandler == null)
                             {
                                 return false;
@@ -174,13 +133,7 @@ namespace Volo.Abp.EventBus
         }
 
         /// <inheritdoc/>
-        public void Unregister<TEvent>(IEventHandler<TEvent> handler) where TEvent : class
-        {
-            Unregister(typeof(TEvent), handler);
-        }
-
-        /// <inheritdoc/>
-        public void AsyncUnregister<TEvent>(IAsyncEventHandler<TEvent> handler) where TEvent : class
+        public void AsyncUnregister<TEvent>(IEventHandler<TEvent> handler) where TEvent : class
         {
             Unregister(typeof(TEvent), handler);
         }
@@ -223,66 +176,6 @@ namespace Volo.Abp.EventBus
             GetOrCreateHandlerFactories(eventType).Locking(factories => factories.Clear());
         }
 
-        /// <inheritdoc/>
-        public void Trigger<TEvent>(TEvent eventData) where TEvent : class
-        {
-            Trigger(typeof(TEvent), eventData);
-        }
-
-        /// <inheritdoc/>
-        public void Trigger(Type eventType, object eventData)
-        {
-            var exceptions = new List<Exception>();
-
-            foreach (var handlerFactories in GetHandlerFactories(eventType))
-            {
-                foreach (var handlerFactory in handlerFactories.EventHandlerFactories)
-                {
-                    var handlerType = handlerFactory.GetHandlerType();
-
-                    if (IsAsyncEventHandler(handlerType))
-                    {
-                        AsyncHelper.RunSync(() => TriggerAsyncHandlingException(handlerFactory, handlerFactories.EventType, eventData, exceptions));
-                    }
-                    else if (IsEventHandler(handlerType))
-                    {
-                        TriggerHandlingException(handlerFactory, handlerFactories.EventType, eventData, exceptions);
-                    }
-                    else
-                    {
-                        var message = $"Event handler to register for event type {eventType.Name} does not implement IEventHandler<{eventType.Name}> or IAsyncEventHandler<{eventType.Name}> interface!";
-                        exceptions.Add(new AbpException(message));
-                    }
-                }
-            }
-
-            //Implements generic argument inheritance. See classWithInheritableGenericArgument
-            if (eventType.GetTypeInfo().IsGenericType &&
-                eventType.GetGenericArguments().Length == 1 &&
-                typeof(IEventDataWithInheritableGenericArgument).IsAssignableFrom(eventType))
-            {
-                var genericArg = eventType.GetGenericArguments()[0];
-                var baseArg = genericArg.GetTypeInfo().BaseType;
-                if (baseArg != null)
-                {
-                    var baseEventType = eventType.GetGenericTypeDefinition().MakeGenericType(baseArg);
-                    var constructorArgs = ((IEventDataWithInheritableGenericArgument)eventData).GetConstructorArgs();
-                    var baseEventData = Activator.CreateInstance(baseEventType, constructorArgs);
-                    Trigger(baseEventType, baseEventData);
-                }
-            }
-
-            if (exceptions.Any())
-            {
-                if (exceptions.Count == 1)
-                {
-                    exceptions[0].ReThrow();
-                }
-
-                throw new AggregateException("More than one error has occurred while triggering the event: " + eventType, exceptions);
-            }
-        }
-
         /// <inheritdoc/>
         public Task TriggerAsync<TEvent>(TEvent eventData) where TEvent : class
         {
@@ -300,21 +193,7 @@ namespace Volo.Abp.EventBus
             {
                 foreach (var handlerFactory in handlerFactories.EventHandlerFactories)
                 {
-                    var handlerType = handlerFactory.GetHandlerType();
-
-                    if (IsAsyncEventHandler(handlerType))
-                    {
-                        await TriggerAsyncHandlingException(handlerFactory, handlerFactories.EventType, eventData, exceptions);
-                    }
-                    else if (IsEventHandler(handlerType))
-                    {
-                        TriggerHandlingException(handlerFactory, handlerFactories.EventType, eventData, exceptions);
-                    }
-                    else
-                    {
-                        var message = $"Event handler to register for event type {eventType.Name} does not implement IEventHandler<{eventType.Name}> or IAsyncEventHandler<{eventType.Name}> interface!";
-                        exceptions.Add(new AbpException(message));
-                    }
+                    await TriggerAsyncHandlingException(handlerFactory, handlerFactories.EventType, eventData, exceptions);
                 }
             }
 
@@ -345,39 +224,13 @@ namespace Volo.Abp.EventBus
             }
         }
 
-        private void TriggerHandlingException(IEventHandlerFactory handlerFactory, Type eventType, object eventData, List<Exception> exceptions)
-        {
-            using (var eventHandlerWrapper = handlerFactory.GetHandler())
-            {
-                try
-                {
-                    var handlerType = typeof(IEventHandler<>).MakeGenericType(eventType);
-
-                    var method = handlerType.GetMethod(
-                        "HandleEvent",
-                        new[] { eventType }
-                    );
-
-                    method.Invoke(eventHandlerWrapper.EventHandler, new[] { eventData });
-                }
-                catch (TargetInvocationException ex)
-                {
-                    exceptions.Add(ex.InnerException);
-                }
-                catch (Exception ex)
-                {
-                    exceptions.Add(ex);
-                }
-            }
-        }
-
         private async Task TriggerAsyncHandlingException(IEventHandlerFactory asyncHandlerFactory, Type eventType, object eventData, List<Exception> exceptions)
         {
             using (var eventHandlerWrapper = asyncHandlerFactory.GetHandler())
             {
                 try
                 {
-                    var asyncHandlerType = typeof(IAsyncEventHandler<>).MakeGenericType(eventType);
+                    var asyncHandlerType = typeof(IEventHandler<>).MakeGenericType(eventType);
 
                     var method = asyncHandlerType.GetMethod(
                         "HandleEventAsync",
@@ -397,20 +250,6 @@ namespace Volo.Abp.EventBus
             }
         }
 
-        private bool IsEventHandler(Type handlerType)
-        {
-            return handlerType.GetInterfaces()
-                .Where(i => i.IsGenericType)
-                .Any(i => i.GetGenericTypeDefinition() == typeof(IEventHandler<>));
-        }
-
-        private bool IsAsyncEventHandler(Type handlerType)
-        {
-            return handlerType.GetInterfaces()
-                .Where(i => i.IsGenericType)
-                .Any(i => i.GetGenericTypeDefinition() == typeof(IAsyncEventHandler<>));
-        }
-
         private IEnumerable<EventTypeWithEventHandlerFactories> GetHandlerFactories(Type eventType)
         {
             var handlerFactoryList = new List<EventTypeWithEventHandlerFactories>();
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IAsyncEventHandler.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IAsyncEventHandler.cs
deleted file mode 100644
index d5336a578f..0000000000
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IAsyncEventHandler.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System.Threading.Tasks;
-
-namespace Volo.Abp.EventBus
-{
-    /// <summary>
-    /// Defines an interface of a class that handles events asynchrounously of type <see cref="IAsyncEventHandler{TEventData}"/>.
-    /// </summary>
-    /// <typeparam name="TEvent">Event type to handle</typeparam>
-    public interface IAsyncEventHandler<in TEvent> : IEventHandler
-    {
-        /// <summary>
-        /// Handler handles the event by implementing this method.
-        /// </summary>
-        /// <param name="eventData">Event data</param>
-        Task HandleEventAsync(TEvent eventData);
-    }
-}
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventBus.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventBus.cs
index 0f12b7a619..993b094ee1 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventBus.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventBus.cs
@@ -8,33 +8,13 @@ namespace Volo.Abp.EventBus
     /// </summary>
     public interface IEventBus
     {
-        #region Register
-
-        /// <summary>
-        /// Registers to an event.
-        /// Given action is called for all event occurrences.
-        /// </summary>
-        /// <param name="action">Action to handle events</param>
-        /// <typeparam name="TEvent">Event type</typeparam>
-        IDisposable Register<TEvent>(Action<TEvent> action) 
-            where TEvent : class;
-
         /// <summary>
         /// Registers to an event.
         /// Given action is called for all event occurrences.
         /// </summary>
         /// <param name="action">Action to handle events</param>
         /// <typeparam name="TEvent">Event type</typeparam>
-        IDisposable AsyncRegister<TEvent>(Func<TEvent, Task> action) 
-            where TEvent : class;
-
-        /// <summary>
-        /// Registers to an event. 
-        /// Same (given) instance of the handler is used for all event occurrences.
-        /// </summary>
-        /// <typeparam name="TEvent">Event type</typeparam>
-        /// <param name="handler">Object to handle the event</param>
-        IDisposable Register<TEvent>(IEventHandler<TEvent> handler) 
+        IDisposable Register<TEvent>(Func<TEvent, Task> action) 
             where TEvent : class;
 
         /// <summary>
@@ -43,7 +23,7 @@ namespace Volo.Abp.EventBus
         /// </summary>
         /// <typeparam name="TEvent">Event type</typeparam>
         /// <param name="handler">Object to handle the event</param>
-        IDisposable AsyncRegister<TEvent>(IAsyncEventHandler<TEvent> handler)
+        IDisposable Register<TEvent>(IEventHandler<TEvent> handler)
             where TEvent : class;
 
         /// <summary>
@@ -80,18 +60,6 @@ namespace Volo.Abp.EventBus
         /// <param name="factory">A factory to create/release handlers</param>
         IDisposable Register(Type eventType, IEventHandlerFactory factory);
 
-        #endregion
-
-        #region Unregister
-
-        /// <summary>
-        /// Unregisters from an event.
-        /// </summary>
-        /// <typeparam name="TEvent">Event type</typeparam>
-        /// <param name="action"></param>
-        void Unregister<TEvent>(Action<TEvent> action) 
-            where TEvent : class;
-
         /// <summary>
         /// Unregisters from an event.
         /// </summary>
@@ -105,15 +73,7 @@ namespace Volo.Abp.EventBus
         /// </summary>
         /// <typeparam name="TEvent">Event type</typeparam>
         /// <param name="handler">Handler object that is registered before</param>
-        void Unregister<TEvent>(IEventHandler<TEvent> handler)
-            where TEvent : class;
-
-        /// <summary>
-        /// Unregisters from an event.
-        /// </summary>
-        /// <typeparam name="TEvent">Event type</typeparam>
-        /// <param name="handler">Handler object that is registered before</param>
-        void AsyncUnregister<TEvent>(IAsyncEventHandler<TEvent> handler) 
+        void AsyncUnregister<TEvent>(IEventHandler<TEvent> handler) 
             where TEvent : class;
 
         /// <summary>
@@ -151,25 +111,6 @@ namespace Volo.Abp.EventBus
         /// <param name="eventType">Event type</param>
         void UnregisterAll(Type eventType);
 
-        #endregion
-
-        #region Trigger
-
-        /// <summary>
-        /// Triggers an event.
-        /// </summary>
-        /// <typeparam name="TEvent">Event type</typeparam>
-        /// <param name="eventData">Related data for the event</param>
-        void Trigger<TEvent>(TEvent eventData) 
-            where TEvent : class;
-
-        /// <summary>
-        /// Triggers an event.
-        /// </summary>
-        /// <param name="eventType">Event type</param>
-        /// <param name="eventData">Related data for the event</param>
-        void Trigger(Type eventType, object eventData);
-
         /// <summary>
         /// Triggers an event asynchronously.
         /// </summary>
@@ -186,7 +127,5 @@ namespace Volo.Abp.EventBus
         /// <param name="eventData">Related data for the event</param>
         /// <returns>The task to handle async operation</returns>
         Task TriggerAsync(Type eventType, object eventData);
-        
-        #endregion
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandler.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandler.cs
index 2d2e72494c..ca3993c6bc 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandler.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandler.cs
@@ -1,8 +1,10 @@
+using System.Threading.Tasks;
+
 namespace Volo.Abp.EventBus
 {
     /// <summary>
     /// Undirect base interface for all event handlers.
-    /// Implement <see cref="IEventHandler{TEventData}"/> instead of this one.
+    /// Implement <see cref="IEventHandler{TEvent}"/> instead of this one.
     /// </summary>
     public interface IEventHandler
     {
@@ -10,7 +12,7 @@ namespace Volo.Abp.EventBus
     }
 
     /// <summary>
-    /// Defines an interface of a class that handles events of type <see cref="IEventHandler{TEventData}"/>.
+    /// Defines an interface of a class that handles events asynchrounously of type <see cref="IEventHandler{TEvent}"/>.
     /// </summary>
     /// <typeparam name="TEvent">Event type to handle</typeparam>
     public interface IEventHandler<in TEvent> : IEventHandler
@@ -19,6 +21,6 @@ namespace Volo.Abp.EventBus
         /// Handler handles the event by implementing this method.
         /// </summary>
         /// <param name="eventData">Event data</param>
-        void HandleEvent(TEvent eventData);
+        Task HandleEventAsync(TEvent eventData);
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandlerFactory.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandlerFactory.cs
index f44b5478cd..9fbb81b014 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandlerFactory.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IEventHandlerFactory.cs
@@ -1,5 +1,3 @@
-using System;
-
 namespace Volo.Abp.EventBus
 {
     /// <summary>
@@ -12,11 +10,5 @@ namespace Volo.Abp.EventBus
         /// </summary>
         /// <returns>The event handler</returns>
         IEventHandlerDisposeWrapper GetHandler();
-
-        /// <summary>
-        /// Gets type of the handler (without creating an instance).
-        /// </summary>
-        /// <returns></returns>
-        Type GetHandlerType();
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IocEventHandlerFactory.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IocEventHandlerFactory.cs
index d93ed291c6..a1749e0e48 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IocEventHandlerFactory.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/IocEventHandlerFactory.cs
@@ -31,10 +31,5 @@ namespace Volo.Abp.EventBus
                 () => scope.Dispose()
             );
         }
-
-        public Type GetHandlerType()
-        {
-            return HandlerType;
-        }
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/NullEventBus.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/NullEventBus.cs
index b15e818831..0edbc06f79 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/NullEventBus.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/NullEventBus.cs
@@ -12,12 +12,7 @@ namespace Volo.Abp.EventBus
             
         }
 
-        public IDisposable Register<TEvent>(Action<TEvent> action) where TEvent : class
-        {
-            return NullDisposable.Instance;
-        }
-
-        public IDisposable AsyncRegister<TEvent>(Func<TEvent, Task> action) where TEvent : class
+        public IDisposable Register<TEvent>(Func<TEvent, Task> action) where TEvent : class
         {
             return NullDisposable.Instance;
         }
@@ -27,11 +22,6 @@ namespace Volo.Abp.EventBus
             return NullDisposable.Instance;
         }
 
-        public IDisposable AsyncRegister<TEvent>(IAsyncEventHandler<TEvent> handler) where TEvent : class
-        {
-            return NullDisposable.Instance;
-        }
-
         public IDisposable Register<TEvent, THandler>() where TEvent : class where THandler : IEventHandler, new()
         {
             return NullDisposable.Instance;
@@ -52,22 +42,12 @@ namespace Volo.Abp.EventBus
             return NullDisposable.Instance;
         }
 
-        public void Unregister<TEvent>(Action<TEvent> action) where TEvent : class
-        {
-
-        }
-
         public void AsyncUnregister<TEvent>(Func<TEvent, Task> action) where TEvent : class
         {
             
         }
 
-        public void Unregister<TEvent>(IEventHandler<TEvent> handler) where TEvent : class
-        {
-            
-        }
-
-        public void AsyncUnregister<TEvent>(IAsyncEventHandler<TEvent> handler) where TEvent : class
+        public void AsyncUnregister<TEvent>(IEventHandler<TEvent> handler) where TEvent : class
         {
             
         }
@@ -97,16 +77,6 @@ namespace Volo.Abp.EventBus
             
         }
 
-        public void Trigger<TEvent>(TEvent eventData) where TEvent : class
-        {
-            
-        }
-
-        public void Trigger(Type eventType, object eventData)
-        {
-            
-        }
-
         public Task TriggerAsync<TEvent>(TEvent eventData) where TEvent : class
         {
             return Task.CompletedTask;
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/SingleInstanceHandlerFactory.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/SingleInstanceHandlerFactory.cs
index e2a0cfe72d..3362084639 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/SingleInstanceHandlerFactory.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/SingleInstanceHandlerFactory.cs
@@ -1,6 +1,3 @@
-using System;
-using Volo.Abp.DynamicProxy;
-
 namespace Volo.Abp.EventBus
 {
     /// <summary>
@@ -30,10 +27,5 @@ namespace Volo.Abp.EventBus
         {
             return new EventHandlerDisposeWrapper(HandlerInstance);
         }
-
-        public Type GetHandlerType()
-        {
-            return ProxyHelper.UnProxy(HandlerInstance).GetType();
-        }
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/TransientEventHandlerFactory.cs b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/TransientEventHandlerFactory.cs
index dc4995a2d9..fe5bf8892e 100644
--- a/src/Volo.Abp.EventBus/Volo/Abp/EventBus/TransientEventHandlerFactory.cs
+++ b/src/Volo.Abp.EventBus/Volo/Abp/EventBus/TransientEventHandlerFactory.cs
@@ -24,10 +24,5 @@ namespace Volo.Abp.EventBus
                 () => (handler as IDisposable)?.Dispose()
             );
         }
-
-        public Type GetHandlerType()
-        {
-            return typeof(THandler);
-        }
     }
 }
\ No newline at end of file
diff --git a/src/Volo.Abp.MongoDB/Volo/Abp/Domain/Repositories/MongoDB/MongoDbRepository.cs b/src/Volo.Abp.MongoDB/Volo/Abp/Domain/Repositories/MongoDB/MongoDbRepository.cs
index d5b2d85039..c099aa2f91 100644
--- a/src/Volo.Abp.MongoDB/Volo/Abp/Domain/Repositories/MongoDB/MongoDbRepository.cs
+++ b/src/Volo.Abp.MongoDB/Volo/Abp/Domain/Repositories/MongoDB/MongoDbRepository.cs
@@ -13,6 +13,7 @@ using Volo.Abp.EventBus;
 using Volo.Abp.Guids;
 using Volo.Abp.MongoDB;
 using Volo.Abp.MultiTenancy;
+using Volo.Abp.Threading;
 
 namespace Volo.Abp.Domain.Repositories.MongoDB
 {
@@ -53,7 +54,7 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
              * This is also true for other "ed" & "ing" events.
              */
 
-            ApplyAbpConceptsForAddedEntity(entity);
+            AsyncHelper.RunSync(() => ApplyAbpConceptsForAddedEntityAsync(entity));
 
             Collection.InsertOne(entity);
 
@@ -65,7 +66,7 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
             bool autoSave = false,
             CancellationToken cancellationToken = default)
         {
-            ApplyAbpConceptsForAddedEntity(entity); //TODO: async?
+            await ApplyAbpConceptsForAddedEntityAsync(entity);
 
             await Collection.InsertOneAsync(
                 entity,
@@ -82,14 +83,14 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
             if (entity is ISoftDelete softDeleteEntity && softDeleteEntity.IsDeleted)
             {
                 SetDeletionAuditProperties(entity);
-                TriggerEntityDeleteEvents(entity);
+                AsyncHelper.RunSync(() => TriggerEntityDeleteEvents(entity));
             }
             else
             {
-                TriggerEntityUpdateEvents(entity);
+                AsyncHelper.RunSync(() => TriggerEntityUpdateEvents(entity));
             }
 
-            TriggerDomainEvents(entity);
+            AsyncHelper.RunSync(() => TriggerDomainEventsAsync(entity));
 
             Collection.ReplaceOne(
                 CreateEntityFilter(entity),
@@ -109,14 +110,14 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
             if (entity is ISoftDelete softDeleteEntity && softDeleteEntity.IsDeleted)
             {
                 SetDeletionAuditProperties(entity);
-                TriggerEntityDeleteEvents(entity);
+                await TriggerEntityDeleteEvents(entity);
             }
             else
             {
-                TriggerEntityUpdateEvents(entity);
+                await TriggerEntityUpdateEvents(entity);
             }
 
-            TriggerDomainEvents(entity);
+            await TriggerDomainEventsAsync(entity);
 
             await Collection.ReplaceOneAsync(
                 CreateEntityFilter(entity),
@@ -129,7 +130,7 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
 
         public override void Delete(TEntity entity, bool autoSave = false)
         {
-            ApplyAbpConceptsForDeletedEntity(entity);
+            AsyncHelper.RunSync(() => ApplyAbpConceptsForDeletedEntityAsync(entity));
 
             if (entity is ISoftDelete softDeleteEntity)
             {
@@ -152,7 +153,7 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
             bool autoSave = false,
             CancellationToken cancellationToken = default)
         {
-            ApplyAbpConceptsForDeletedEntity(entity);
+            await ApplyAbpConceptsForDeletedEntityAsync(entity);
 
             if (entity is ISoftDelete softDeleteEntity)
             {
@@ -220,37 +221,37 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
             );
         }
 
-        protected virtual void ApplyAbpConceptsForAddedEntity(TEntity entity)
+        protected virtual async Task ApplyAbpConceptsForAddedEntityAsync(TEntity entity)
         {
             CheckAndSetId(entity);
             SetCreationAuditProperties(entity);
-            TriggerEntityCreateEvents(entity);
-            TriggerDomainEvents(entity);
+            await TriggerEntityCreateEvents(entity);
+            await TriggerDomainEventsAsync(entity);
         }
 
-        private void TriggerEntityCreateEvents(TEntity entity)
+        private async Task TriggerEntityCreateEvents(TEntity entity)
         {
-            EntityChangeEventHelper.TriggerEntityCreatedEventOnUowCompleted(entity);
-            EntityChangeEventHelper.TriggerEntityCreatingEvent(entity);
+            await EntityChangeEventHelper.TriggerEntityCreatedEventOnUowCompletedAsync(entity);
+            await EntityChangeEventHelper.TriggerEntityCreatingEventAsync(entity);
         }
 
-        protected virtual void TriggerEntityUpdateEvents(TEntity entity)
+        protected virtual async Task TriggerEntityUpdateEvents(TEntity entity)
         {
-            EntityChangeEventHelper.TriggerEntityUpdatedEventOnUowCompleted(entity);
-            EntityChangeEventHelper.TriggerEntityUpdatingEvent(entity);
+            await EntityChangeEventHelper.TriggerEntityUpdatedEventOnUowCompletedAsync(entity);
+            await EntityChangeEventHelper.TriggerEntityUpdatingEventAsync(entity);
         }
 
-        protected virtual void ApplyAbpConceptsForDeletedEntity(TEntity entity)
+        protected virtual async Task ApplyAbpConceptsForDeletedEntityAsync(TEntity entity)
         {
             SetDeletionAuditProperties(entity);
-            TriggerEntityDeleteEvents(entity);
-            TriggerDomainEvents(entity);
+            await TriggerEntityDeleteEvents(entity);
+            await TriggerDomainEventsAsync(entity);
         }
 
-        protected virtual void TriggerEntityDeleteEvents(TEntity entity)
+        protected virtual async Task TriggerEntityDeleteEvents(TEntity entity)
         {
-            EntityChangeEventHelper.TriggerEntityDeletedEventOnUowCompleted(entity);
-            EntityChangeEventHelper.TriggerEntityDeletingEvent(entity);
+            await EntityChangeEventHelper.TriggerEntityDeletedEventOnUowCompletedAsync(entity);
+            await EntityChangeEventHelper.TriggerEntityDeletingEventAsync(entity);
         }
 
         protected virtual void CheckAndSetId(TEntity entity)
@@ -276,8 +277,7 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
             AuditPropertySetter.SetDeletionProperties(entity);
         }
 
-        //TODO: TriggerDomainEventsAsync..?
-        protected virtual void TriggerDomainEvents(object entity)
+        protected virtual async Task TriggerDomainEventsAsync(object entity)
         {
             var generatesDomainEventsEntity = entity as IGeneratesDomainEvents;
             if (generatesDomainEventsEntity == null)
@@ -293,7 +293,7 @@ namespace Volo.Abp.Domain.Repositories.MongoDB
 
             foreach (var entityEvent in entityEvents)
             {
-                EventBus.Trigger(entityEvent.GetType(), entityEvent);
+                await EventBus.TriggerAsync(entityEvent.GetType(), entityEvent);
             }
 
             generatesDomainEventsEntity.ClearDomainEvents();
diff --git a/src/Volo.Abp.Uow/Volo/Abp/Uow/ChildUnitOfWork.cs b/src/Volo.Abp.Uow/Volo/Abp/Uow/ChildUnitOfWork.cs
index cd19361c88..d46893d590 100644
--- a/src/Volo.Abp.Uow/Volo/Abp/Uow/ChildUnitOfWork.cs
+++ b/src/Volo.Abp.Uow/Volo/Abp/Uow/ChildUnitOfWork.cs
@@ -17,7 +17,6 @@ namespace Volo.Abp.Uow
 
         public string ReservationName => _parent.ReservationName;
 
-        public event EventHandler<UnitOfWorkEventArgs> Completed;
         public event EventHandler<UnitOfWorkFailedEventArgs> Failed;
         public event EventHandler<UnitOfWorkEventArgs> Disposed;
 
@@ -31,7 +30,6 @@ namespace Volo.Abp.Uow
 
             _parent = parent;
 
-            _parent.Completed += (sender, args) => { Completed.InvokeSafely(sender, args); };
             _parent.Failed += (sender, args) => { Failed.InvokeSafely(sender, args); };
             _parent.Disposed += (sender, args) => { Disposed.InvokeSafely(sender, args); };
         }
@@ -81,6 +79,11 @@ namespace Volo.Abp.Uow
             return _parent.RollbackAsync(cancellationToken);
         }
 
+        public void OnCompleted(Func<Task> handler)
+        {
+            _parent.OnCompleted(handler);
+        }
+
         public IDatabaseApi FindDatabaseApi(string key)
         {
             return _parent.FindDatabaseApi(key);
diff --git a/src/Volo.Abp.Uow/Volo/Abp/Uow/IUnitOfWork.cs b/src/Volo.Abp.Uow/Volo/Abp/Uow/IUnitOfWork.cs
index 4b21a51fca..6fe2546965 100644
--- a/src/Volo.Abp.Uow/Volo/Abp/Uow/IUnitOfWork.cs
+++ b/src/Volo.Abp.Uow/Volo/Abp/Uow/IUnitOfWork.cs
@@ -9,8 +9,7 @@ namespace Volo.Abp.Uow
     {
         Guid Id { get; }
 
-        event EventHandler<UnitOfWorkEventArgs> Completed;
-
+        //TODO: Switch to OnFailed (sync) and OnDisposed (sync) methods to be compatible with OnCompleted
         event EventHandler<UnitOfWorkFailedEventArgs> Failed;
 
         event EventHandler<UnitOfWorkEventArgs> Disposed;
@@ -40,5 +39,7 @@ namespace Volo.Abp.Uow
         void Rollback();
 
         Task RollbackAsync(CancellationToken cancellationToken = default);
+
+        void OnCompleted(Func<Task> handler);
     }
 }
diff --git a/src/Volo.Abp.Uow/Volo/Abp/Uow/UnitOfWork.cs b/src/Volo.Abp.Uow/Volo/Abp/Uow/UnitOfWork.cs
index b0e7f0b739..3f5a9cebf7 100644
--- a/src/Volo.Abp.Uow/Volo/Abp/Uow/UnitOfWork.cs
+++ b/src/Volo.Abp.Uow/Volo/Abp/Uow/UnitOfWork.cs
@@ -4,6 +4,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Options;
 using Volo.Abp.DependencyInjection;
+using Volo.Abp.Threading;
 
 namespace Volo.Abp.Uow
 {
@@ -19,7 +20,8 @@ namespace Volo.Abp.Uow
 
         public string ReservationName { get; set; }
 
-        public event EventHandler<UnitOfWorkEventArgs> Completed;
+        protected List<Func<Task>> CompletedHandlers { get; } = new List<Func<Task>>();
+
         public event EventHandler<UnitOfWorkFailedEventArgs> Failed;
         public event EventHandler<UnitOfWorkEventArgs> Disposed;
 
@@ -123,7 +125,7 @@ namespace Volo.Abp.Uow
             {
                 await SaveChangesAsync(cancellationToken);
                 await CommitTransactionsAsync();
-                OnCompleted();
+                await OnCompletedAsync();
             }
             catch (Exception ex)
             {
@@ -210,9 +212,30 @@ namespace Volo.Abp.Uow
             return _transactionApis.GetOrAdd(key, factory);
         }
 
+        public void OnCompleted(Func<Task> handler)
+        {
+            CompletedHandlers.Add(handler);
+        }
+
+        public void OnFailed(Func<Task> handler)
+        {
+            throw new NotImplementedException();
+        }
+
         protected virtual void OnCompleted()
         {
-            Completed.InvokeSafely(this, new UnitOfWorkEventArgs(this));
+            foreach (var handler in CompletedHandlers)
+            {
+                AsyncHelper.RunSync(handler);
+            }
+        }
+
+        protected virtual async Task OnCompletedAsync()
+        {
+            foreach (var handler in CompletedHandlers)
+            {
+                await handler.Invoke();
+            }
         }
 
         protected virtual void OnFailed()
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/ActionBasedEventHandlerTest.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/ActionBasedEventHandlerTest.cs
index 954b134c73..bc4121c991 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/ActionBasedEventHandlerTest.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/ActionBasedEventHandlerTest.cs
@@ -8,7 +8,7 @@ namespace Volo.Abp.EventBus
     public class ActionBasedEventHandlerTest : EventBusTestBase
     {
         [Fact]
-        public void Should_Call_Action_On_Event_With_Correct_Source()
+        public async Task Should_Call_Action_On_Event_With_Correct_Source()
         {
             var totalData = 0;
 
@@ -16,18 +16,19 @@ namespace Volo.Abp.EventBus
                 eventData =>
                 {
                     totalData += eventData.Value;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(new MySimpleEventData(1));
-            EventBus.Trigger(new MySimpleEventData(2));
-            EventBus.Trigger(new MySimpleEventData(3));
-            EventBus.Trigger(new MySimpleEventData(4));
+            await EventBus.TriggerAsync(new MySimpleEventData(1));
+            await EventBus.TriggerAsync(new MySimpleEventData(2));
+            await EventBus.TriggerAsync(new MySimpleEventData(3));
+            await EventBus.TriggerAsync(new MySimpleEventData(4));
 
             Assert.Equal(10, totalData);
         }
 
         [Fact]
-        public void Should_Call_Handler_With_Non_Generic_Trigger()
+        public async Task Should_Call_Handler_With_Non_Generic_Trigger()
         {
             var totalData = 0;
 
@@ -35,18 +36,19 @@ namespace Volo.Abp.EventBus
                 eventData =>
                 {
                     totalData += eventData.Value;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(typeof(MySimpleEventData), new MySimpleEventData(1));
-            EventBus.Trigger(typeof(MySimpleEventData), new MySimpleEventData(2));
-            EventBus.Trigger(typeof(MySimpleEventData), new MySimpleEventData(3));
-            EventBus.Trigger(typeof(MySimpleEventData), new MySimpleEventData(4));
+            await EventBus.TriggerAsync(typeof(MySimpleEventData), new MySimpleEventData(1));
+            await EventBus.TriggerAsync(typeof(MySimpleEventData), new MySimpleEventData(2));
+            await EventBus.TriggerAsync(typeof(MySimpleEventData), new MySimpleEventData(3));
+            await EventBus.TriggerAsync(typeof(MySimpleEventData), new MySimpleEventData(4));
 
             Assert.Equal(10, totalData);
         }
 
         [Fact]
-        public void Should_Not_Call_Action_After_Unregister_1()
+        public async Task Should_Not_Call_Action_After_Unregister_1()
         {
             var totalData = 0;
 
@@ -54,39 +56,41 @@ namespace Volo.Abp.EventBus
                 eventData =>
                 {
                     totalData += eventData.Value;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(new MySimpleEventData(1));
-            EventBus.Trigger(new MySimpleEventData(2));
-            EventBus.Trigger(new MySimpleEventData(3));
+            await EventBus.TriggerAsync(new MySimpleEventData(1));
+            await EventBus.TriggerAsync(new MySimpleEventData(2));
+            await EventBus.TriggerAsync(new MySimpleEventData(3));
 
             registerDisposer.Dispose();
 
-            EventBus.Trigger(new MySimpleEventData(4));
+            await EventBus.TriggerAsync(new MySimpleEventData(4));
 
             Assert.Equal(6, totalData);
         }
 
         [Fact]
-        public void Should_Not_Call_Action_After_Unregister_2()
+        public async Task Should_Not_Call_Action_After_Unregister_2()
         {
             var totalData = 0;
 
-            var action = new Action<MySimpleEventData>(
+            var action = new Func<MySimpleEventData, Task>(
                 eventData =>
                 {
                     totalData += eventData.Value;
+                    return Task.CompletedTask;
                 });
 
             EventBus.Register(action);
 
-            EventBus.Trigger(new MySimpleEventData(1));
-            EventBus.Trigger(new MySimpleEventData(2));
-            EventBus.Trigger(new MySimpleEventData(3));
+            await EventBus.TriggerAsync(new MySimpleEventData(1));
+            await EventBus.TriggerAsync(new MySimpleEventData(2));
+            await EventBus.TriggerAsync(new MySimpleEventData(3));
 
-            EventBus.Unregister(action);
+            EventBus.AsyncUnregister(action);
 
-            EventBus.Trigger(new MySimpleEventData(4));
+            await EventBus.TriggerAsync(new MySimpleEventData(4));
 
             Assert.Equal(6, totalData);
         }
@@ -96,7 +100,7 @@ namespace Volo.Abp.EventBus
         {
             int totalData = 0;
 
-            EventBus.AsyncRegister<MySimpleEventData>(
+            EventBus.Register<MySimpleEventData>(
                 async eventData =>
                 {
                     await Task.Delay(20);
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_DI_Services_Test.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_DI_Services_Test.cs
index 21af339052..0567522d68 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_DI_Services_Test.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_DI_Services_Test.cs
@@ -9,13 +9,12 @@ namespace Volo.Abp.EventBus
         [Fact]
         public async Task Should_Automatically_Register_EventHandlers_From_Services()
         {
-            EventBus.Trigger(new MySimpleEventData(1));
+            await EventBus.TriggerAsync(new MySimpleEventData(1));
             await EventBus.TriggerAsync(new MySimpleEventData(2));
-            EventBus.Trigger(new MySimpleEventData(3));
+            await EventBus.TriggerAsync(new MySimpleEventData(3));
             await EventBus.TriggerAsync(new MySimpleEventData(4));
 
             GetRequiredService<MySimpleEventDataHandler>().TotalData.ShouldBe(10);
-            GetRequiredService<MySimpleAsyncEventDataHandler>().TotalData.ShouldBe(10);
         }
     }
 }
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_Exception_Test.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_Exception_Test.cs
index 31d0b4dfbe..9613580b6b 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_Exception_Test.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_Exception_Test.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 using Shouldly;
 using Xunit;
 
@@ -7,21 +8,20 @@ namespace Volo.Abp.EventBus
     public class EventBus_Exception_Test : EventBusTestBase
     {
         [Fact]
-        public void Should_Throw_Single_Exception_If_Only_One_Of_Handlers_Fails()
+        public async Task Should_Throw_Single_Exception_If_Only_One_Of_Handlers_Fails()
         {
-            EventBus.Register<MySimpleEventData>(
-                eventData => throw new Exception("This exception is intentionally thrown!"));
+            EventBus.Register<MySimpleEventData>(eventData => throw new Exception("This exception is intentionally thrown!"));
 
-            var appException = Assert.Throws<Exception>(() =>
+            var appException = await Assert.ThrowsAsync<Exception>(async () =>
             {
-                EventBus.Trigger(new MySimpleEventData(1));
+                await EventBus.TriggerAsync(new MySimpleEventData(1));
             });
 
             appException.Message.ShouldBe("This exception is intentionally thrown!");
         }
 
         [Fact]
-        public void Should_Throw_Aggregate_Exception_If_More_Than_One_Of_Handlers_Fail()
+        public async Task Should_Throw_Aggregate_Exception_If_More_Than_One_Of_Handlers_Fail()
         {
             EventBus.Register<MySimpleEventData>(
                 eventData => throw new Exception("This exception is intentionally thrown #1!"));
@@ -29,9 +29,9 @@ namespace Volo.Abp.EventBus
             EventBus.Register<MySimpleEventData>(
                 eventData => throw new Exception("This exception is intentionally thrown #2!"));
 
-            var aggrException = Assert.Throws<AggregateException>(() =>
+            var aggrException = await Assert.ThrowsAsync<AggregateException>(async () =>
             {
-                EventBus.Trigger(new MySimpleEventData(1));
+                await EventBus.TriggerAsync(new MySimpleEventData(1));
             });
 
             aggrException.InnerExceptions.Count.ShouldBe(2);
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_MultipleHandle_Test.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_MultipleHandle_Test.cs
index 289f226dd2..78df6a6b40 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_MultipleHandle_Test.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/EventBus_MultipleHandle_Test.cs
@@ -9,25 +9,17 @@ namespace Volo.Abp.EventBus
     public class EventBus_EntityEvents_Test : EventBusTestBase
     {
         [Fact]
-        public void Should_Call_Created_And_Changed_Once()
+        public async Task Should_Call_Created_And_Changed_Once()
         {
             var handler = new MyEventHandler();
 
             EventBus.Register<EntityChangedEventData<MyEntity>>(handler);
             EventBus.Register<EntityCreatedEventData<MyEntity>>(handler);
 
-            var asyncHandler = new MyAsyncEventHandler();
-
-            EventBus.AsyncRegister<EntityChangedEventData<MyEntity>>(asyncHandler);
-            EventBus.AsyncRegister<EntityCreatedEventData<MyEntity>>(asyncHandler);
-
-            EventBus.Trigger(new EntityCreatedEventData<MyEntity>(new MyEntity()));
+            await EventBus.TriggerAsync(new EntityCreatedEventData<MyEntity>(new MyEntity()));
 
             handler.EntityCreatedEventCount.ShouldBe(1);
             handler.EntityChangedEventCount.ShouldBe(1);
-
-            asyncHandler.EntityCreatedEventCount.ShouldBe(1);
-            asyncHandler.EntityChangedEventCount.ShouldBe(1);
         }
 
         public class MyEntity : Entity
@@ -35,41 +27,23 @@ namespace Volo.Abp.EventBus
             
         }
 
-        public class MyEventHandler : 
+        public class MyEventHandler :
             IEventHandler<EntityChangedEventData<MyEntity>>,
             IEventHandler<EntityCreatedEventData<MyEntity>>
         {
             public int EntityChangedEventCount { get; set; }
             public int EntityCreatedEventCount { get; set; }
 
-            public void HandleEvent(EntityChangedEventData<MyEntity> eventData)
-            {
-                EntityChangedEventCount++;
-            }
-
-            public void HandleEvent(EntityCreatedEventData<MyEntity> eventData)
-            {
-                EntityCreatedEventCount++;
-            }
-        }
-
-        public class MyAsyncEventHandler :
-            IAsyncEventHandler<EntityChangedEventData<MyEntity>>,
-            IAsyncEventHandler<EntityCreatedEventData<MyEntity>>
-        {
-            public int EntityChangedEventCount { get; set; }
-            public int EntityCreatedEventCount { get; set; }
-
             public Task HandleEventAsync(EntityChangedEventData<MyEntity> eventData)
             {
                 EntityChangedEventCount++;
-                return Task.FromResult(0);
+                return Task.CompletedTask;
             }
 
             public Task HandleEventAsync(EntityCreatedEventData<MyEntity> eventData)
             {
                 EntityCreatedEventCount++;
-                return Task.FromResult(0);
+                return Task.CompletedTask;
             }
         }
     }
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/GenericInheritanceTest.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/GenericInheritanceTest.cs
index d59a29b648..4a3fbccce8 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/GenericInheritanceTest.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/GenericInheritanceTest.cs
@@ -1,3 +1,4 @@
+using System.Threading.Tasks;
 using Shouldly;
 using Volo.Abp.Domain.Entities;
 using Volo.Abp.Domain.Entities.Events;
@@ -8,7 +9,7 @@ namespace Volo.Abp.EventBus
     public class GenericInheritanceTest : EventBusTestBase
     {
         [Fact]
-        public void Should_Trigger_For_Inherited_Generic_1()
+        public async Task Should_Trigger_For_Inherited_Generic_1()
         {
             var triggeredEvent = false;
 
@@ -17,15 +18,16 @@ namespace Volo.Abp.EventBus
                 {
                     eventData.Entity.Id.ShouldBe(42);
                     triggeredEvent = true;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(new EntityUpdatedEventData<Person>(new Person { Id = 42 }));
+            await EventBus.TriggerAsync(new EntityUpdatedEventData<Person>(new Person { Id = 42 }));
 
             triggeredEvent.ShouldBe(true);
         }
 
         [Fact]
-        public void Should_Trigger_For_Inherited_Generic_2()
+        public async Task Should_Trigger_For_Inherited_Generic_2()
         {
             var triggeredEvent = false;
 
@@ -34,14 +36,14 @@ namespace Volo.Abp.EventBus
                 {
                     eventData.Entity.Id.ShouldBe(42);
                     triggeredEvent = true;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(new EntityChangedEventData<Student>(new Student { Id = 42 }));
+            await EventBus.TriggerAsync(new EntityChangedEventData<Student>(new Student { Id = 42 }));
 
             triggeredEvent.ShouldBe(true);
         }
         
-        
         public class Person : Entity<int>
         {
             
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/InheritanceTest.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/InheritanceTest.cs
index 9f6a26f89b..5168e11054 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/InheritanceTest.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/InheritanceTest.cs
@@ -1,3 +1,4 @@
+using System.Threading.Tasks;
 using Xunit;
 
 namespace Volo.Abp.EventBus
@@ -5,7 +6,7 @@ namespace Volo.Abp.EventBus
     public class InheritanceTest : EventBusTestBase
     {
         [Fact]
-        public void Should_Handle_Events_For_Derived_Classes()
+        public async Task Should_Handle_Events_For_Derived_Classes()
         {
             var totalData = 0;
 
@@ -13,18 +14,19 @@ namespace Volo.Abp.EventBus
                 eventData =>
                 {
                     totalData += eventData.Value;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(new MySimpleEventData(1)); //Should handle directly registered class
-            EventBus.Trigger(new MySimpleEventData(2)); //Should handle directly registered class
-            EventBus.Trigger(new MyDerivedEventData(3)); //Should handle derived class too
-            EventBus.Trigger(new MyDerivedEventData(4)); //Should handle derived class too
+            await EventBus.TriggerAsync(new MySimpleEventData(1)); //Should handle directly registered class
+            await EventBus.TriggerAsync(new MySimpleEventData(2)); //Should handle directly registered class
+            await EventBus.TriggerAsync(new MyDerivedEventData(3)); //Should handle derived class too
+            await EventBus.TriggerAsync(new MyDerivedEventData(4)); //Should handle derived class too
 
             Assert.Equal(10, totalData);
         }
 
         [Fact]
-        public void Should_Not_Handle_Events_For_Base_Classes()
+        public async Task Should_Not_Handle_Events_For_Base_Classes()
         {
             var totalData = 0;
 
@@ -32,12 +34,13 @@ namespace Volo.Abp.EventBus
                 eventData =>
                 {
                     totalData += eventData.Value;
+                    return Task.CompletedTask;
                 });
 
-            EventBus.Trigger(new MySimpleEventData(1)); //Should not handle
-            EventBus.Trigger(new MySimpleEventData(2)); //Should not handle
-            EventBus.Trigger(new MyDerivedEventData(3)); //Should handle
-            EventBus.Trigger(new MyDerivedEventData(4)); //Should handle
+            await EventBus.TriggerAsync(new MySimpleEventData(1)); //Should not handle
+            await EventBus.TriggerAsync(new MySimpleEventData(2)); //Should not handle
+            await EventBus.TriggerAsync(new MyDerivedEventData(3)); //Should handle
+            await EventBus.TriggerAsync(new MyDerivedEventData(4)); //Should handle
 
             Assert.Equal(7, totalData);
         }   
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleAsyncEventDataHandler.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleAsyncEventDataHandler.cs
deleted file mode 100644
index b8f6802fe6..0000000000
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleAsyncEventDataHandler.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-using System.Threading.Tasks;
-using Volo.Abp.DependencyInjection;
-
-namespace Volo.Abp.EventBus
-{
-    public class MySimpleAsyncEventDataHandler : IAsyncEventHandler<MySimpleEventData>, ISingletonDependency
-    {
-        public int TotalData { get; private set; }
-
-        public Task HandleEventAsync(MySimpleEventData eventData)
-        {
-            TotalData += eventData.Value;
-            return Task.CompletedTask;
-        }
-    }
-}
\ No newline at end of file
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleEventDataHandler.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleEventDataHandler.cs
index d694cee971..700a68ef05 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleEventDataHandler.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleEventDataHandler.cs
@@ -1,4 +1,5 @@
-using Volo.Abp.DependencyInjection;
+using System.Threading.Tasks;
+using Volo.Abp.DependencyInjection;
 
 namespace Volo.Abp.EventBus
 {
@@ -6,9 +7,10 @@ namespace Volo.Abp.EventBus
     {
         public int TotalData { get; private set; }
 
-        public void HandleEvent(MySimpleEventData eventData)
+        public Task HandleEventAsync(MySimpleEventData eventData)
         {
             TotalData += eventData.Value;
+            return Task.CompletedTask;
         }
     }
 }
\ No newline at end of file
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientAsyncEventHandler.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientAsyncEventHandler.cs
deleted file mode 100644
index 755df57faa..0000000000
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientAsyncEventHandler.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-using System;
-using System.Threading.Tasks;
-
-namespace Volo.Abp.EventBus
-{
-    public class MySimpleTransientAsyncEventHandler : IAsyncEventHandler<MySimpleEventData>, IDisposable
-    {
-        public static int HandleCount { get; set; }
-
-        public static int DisposeCount { get; set; }
-
-        public Task HandleEventAsync(MySimpleEventData eventData)
-        {
-            ++HandleCount;
-            return Task.FromResult(0);
-        }
-
-        public void Dispose()
-        {
-            ++DisposeCount;
-        }
-    }
-}
\ No newline at end of file
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientEventHandler.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientEventHandler.cs
index 2ef07fe500..be2b98026f 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientEventHandler.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/MySimpleTransientEventHandler.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 namespace Volo.Abp.EventBus
 {
@@ -8,9 +9,10 @@ namespace Volo.Abp.EventBus
 
         public static int DisposeCount { get; set; }
 
-        public void HandleEvent(MySimpleEventData eventData)
+        public Task HandleEventAsync(MySimpleEventData eventData)
         {
             ++HandleCount;
+            return Task.CompletedTask;
         }
 
         public void Dispose()
diff --git a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/TransientDisposableEventHandlerTest.cs b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/TransientDisposableEventHandlerTest.cs
index 4b62c62363..3250128ea8 100644
--- a/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/TransientDisposableEventHandlerTest.cs
+++ b/test/Volo.Abp.EventBus.Tests/Volo/Abp/EventBus/TransientDisposableEventHandlerTest.cs
@@ -1,3 +1,4 @@
+using System.Threading.Tasks;
 using Xunit;
 
 namespace Volo.Abp.EventBus
@@ -5,20 +6,16 @@ namespace Volo.Abp.EventBus
     public class TransientDisposableEventHandlerTest : EventBusTestBase
     {
         [Fact]
-        public void Should_Call_Handler_AndDispose()
+        public async Task Should_Call_Handler_AndDispose()
         {
             EventBus.Register<MySimpleEventData, MySimpleTransientEventHandler>();
-            EventBus.Register<MySimpleEventData, MySimpleTransientAsyncEventHandler>();
 
-            EventBus.Trigger(new MySimpleEventData(1));
-            EventBus.Trigger(new MySimpleEventData(2));
-            EventBus.Trigger(new MySimpleEventData(3));
+            await EventBus.TriggerAsync(new MySimpleEventData(1));
+            await EventBus.TriggerAsync(new MySimpleEventData(2));
+            await EventBus.TriggerAsync(new MySimpleEventData(3));
 
             Assert.Equal(3, MySimpleTransientEventHandler.HandleCount);
             Assert.Equal(3, MySimpleTransientEventHandler.DisposeCount);
-
-            Assert.Equal(3, MySimpleTransientAsyncEventHandler.HandleCount);
-            Assert.Equal(3, MySimpleTransientAsyncEventHandler.DisposeCount);
         }
     }
 }
\ No newline at end of file
diff --git a/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/DomainEvents_Tests.cs b/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/DomainEvents_Tests.cs
index aa0f4e83e6..38e219677f 100644
--- a/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/DomainEvents_Tests.cs
+++ b/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/DomainEvents_Tests.cs
@@ -29,11 +29,12 @@ namespace Volo.Abp.TestApp.Testing
 
             var isTriggered = false;
 
-            EventBus.Register<PersonNameChangedEvent>((data) =>
+            EventBus.Register<PersonNameChangedEvent>(data =>
             {
                 data.OldName.ShouldBe("Douglas");
                 data.Person.Name.ShouldBe("Douglas-Changed");
                 isTriggered = true;
+                return Task.CompletedTask;
             });
 
             //Act
diff --git a/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/EntityChangeEvents_Tests.cs b/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/EntityChangeEvents_Tests.cs
index ca363a8730..a945120a43 100644
--- a/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/EntityChangeEvents_Tests.cs
+++ b/test/Volo.Abp.TestApp/Volo/Abp/TestApp/Testing/EntityChangeEvents_Tests.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 using Shouldly;
 using Volo.Abp.Domain.Entities.Events;
 using Volo.Abp.Domain.Repositories;
@@ -50,6 +51,7 @@ namespace Volo.Abp.TestApp.Testing
                     data.Entity.Age.ShouldBe(15);
                     data.Entity.Age = 18;
                     PersonRepository.Update(data.Entity);
+                    return Task.CompletedTask;
                 });
 
                 EventBus.Register<EntityCreatedEventData<Person>>(data =>
@@ -63,6 +65,8 @@ namespace Volo.Abp.TestApp.Testing
 
                     data.Entity.Age.ShouldBe(18);
                     data.Entity.Name.ShouldBe(personName);
+
+                    return Task.CompletedTask;
                 });
 
                 EventBus.Register<EntityUpdatingEventData<Person>>(data =>
@@ -76,6 +80,8 @@ namespace Volo.Abp.TestApp.Testing
 
                     data.Entity.Name.ShouldBe(personName);
                     data.Entity.Age.ShouldBe(18);
+
+                    return Task.CompletedTask;
                 });
 
                 EventBus.Register<EntityUpdatedEventData<Person>>(data =>
@@ -89,6 +95,8 @@ namespace Volo.Abp.TestApp.Testing
 
                     data.Entity.Name.ShouldBe(personName);
                     data.Entity.Age.ShouldBe(18);
+
+                    return Task.CompletedTask;
                 });
 
                 PersonRepository.Insert(new Person(Guid.NewGuid(), personName, 15));
diff --git a/test/Volo.Abp.Uow.Tests/Volo/Abp/Uow/UnitOfWork_Events_Tests.cs b/test/Volo.Abp.Uow.Tests/Volo/Abp/Uow/UnitOfWork_Events_Tests.cs
index fdc2ca62a8..4d9bfc8dd6 100644
--- a/test/Volo.Abp.Uow.Tests/Volo/Abp/Uow/UnitOfWork_Events_Tests.cs
+++ b/test/Volo.Abp.Uow.Tests/Volo/Abp/Uow/UnitOfWork_Events_Tests.cs
@@ -22,7 +22,7 @@ namespace Volo.Abp.Uow
 
             using (var uow = _unitOfWorkManager.Begin())
             {
-                uow.Completed += (sender, args) => completed = true;
+                uow.OnCompleted(async () => completed = true);
                 uow.Disposed += (sender, args) => disposed = true;
 
                 uow.Complete();
@@ -43,7 +43,7 @@ namespace Volo.Abp.Uow
             {
                 using (var childUow = _unitOfWorkManager.Begin())
                 {
-                    childUow.Completed += (sender, args) => completed = true;
+                    childUow.OnCompleted(async () => completed = true);
                     uow.Disposed += (sender, args) => disposed = true;
 
                     childUow.Complete();
@@ -73,7 +73,7 @@ namespace Volo.Abp.Uow
 
             using (var uow = _unitOfWorkManager.Begin())
             {
-                uow.Completed += (sender, args) => completed = true;
+                uow.OnCompleted(async () => completed = true);
                 uow.Failed += (sender, args) => failed = true;
                 uow.Disposed += (sender, args) => disposed = true;
             }
@@ -94,7 +94,7 @@ namespace Volo.Abp.Uow
             {
                 using (var uow = _unitOfWorkManager.Begin())
                 {
-                    uow.Completed += (sender, args) => completed = true;
+                    uow.OnCompleted(async () => completed = true);
                     uow.Failed += (sender, args) => failed = true;
                     uow.Disposed += (sender, args) => disposed = true;
 
@@ -118,7 +118,7 @@ namespace Volo.Abp.Uow
 
             using (var uow = _unitOfWorkManager.Begin())
             {
-                uow.Completed += (sender, args) => completed = true;
+                uow.OnCompleted(async () => completed = true);
                 uow.Failed += (sender, args) => { failed = true; args.IsRolledback.ShouldBeTrue(); };
                 uow.Disposed += (sender, args) => disposed = true;