diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo.Abp.ExceptionHandling.csproj b/framework/src/Volo.Abp.ExceptionHandling/Volo.Abp.ExceptionHandling.csproj
index 96c708d6c6..142b143632 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo.Abp.ExceptionHandling.csproj
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo.Abp.ExceptionHandling.csproj
@@ -5,6 +5,8 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+        <Nullable>enable</Nullable>
+        <WarningsAsErrors>Nullable</WarningsAsErrors>
         <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
         <RootNamespace />
     </PropertyGroup>
diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/DefaultExceptionToErrorInfoConverter.cs b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/DefaultExceptionToErrorInfoConverter.cs
index 1b8742af81..b068890b97 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/DefaultExceptionToErrorInfoConverter.cs
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/DefaultExceptionToErrorInfoConverter.cs
@@ -54,7 +54,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         return errorInfo;
     }
 
-    public RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions> options = null)
+    public RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions>? options = null)
     {
         var exceptionHandlingOptions = CreateDefaultOptions();
         options?.Invoke(exceptionHandlingOptions);
@@ -90,7 +90,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
         if (exception is EntityNotFoundException)
         {
-            return CreateEntityNotFoundError(exception as EntityNotFoundException);
+            return CreateEntityNotFoundError((exception as EntityNotFoundException)!);
         }
 
         var errorInfo = new RemoteServiceErrorInfo();
@@ -110,10 +110,10 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
             if (errorInfo.Details.IsNullOrEmpty())
             {
-                errorInfo.Details = GetValidationErrorNarrative(exception as IHasValidationErrors);
+                errorInfo.Details = GetValidationErrorNarrative((exception as IHasValidationErrors)!);
             }
 
-            errorInfo.ValidationErrors = GetValidationErrorInfos(exception as IHasValidationErrors);
+            errorInfo.ValidationErrors = GetValidationErrorInfos((exception as IHasValidationErrors)!);
         }
 
         TryToLocalizeExceptionMessage(exception, errorInfo);
@@ -146,7 +146,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         }
 
         if (exceptionWithErrorCode.Code.IsNullOrWhiteSpace() ||
-            !exceptionWithErrorCode.Code.Contains(":"))
+            !exceptionWithErrorCode.Code!.Contains(":"))
         {
             return;
         }
@@ -197,10 +197,8 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
     protected virtual Exception TryToGetActualException(Exception exception)
     {
-        if (exception is AggregateException && exception.InnerException != null)
+        if (exception is AggregateException aggException && aggException.InnerException != null)
         {
-            var aggException = exception as AggregateException;
-
             if (aggException.InnerException is AbpValidationException ||
                 aggException.InnerException is AbpAuthorizationException ||
                 aggException.InnerException is EntityNotFoundException ||
@@ -223,7 +221,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
         if (exception is AbpValidationException)
         {
-            errorInfo.ValidationErrors = GetValidationErrorInfos(exception as AbpValidationException);
+            errorInfo.ValidationErrors = GetValidationErrorInfos((exception as AbpValidationException)!);
         }
 
         return errorInfo;
@@ -246,9 +244,8 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         }
 
         //Additional info for AbpValidationException
-        if (exception is AbpValidationException)
+        if (exception is AbpValidationException validationException)
         {
-            var validationException = exception as AbpValidationException;
             if (validationException.ValidationErrors.Count > 0)
             {
                 detailBuilder.AppendLine(GetValidationErrorNarrative(validationException));
@@ -268,9 +265,8 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
         }
 
         //Inner exceptions for AggregateException
-        if (exception is AggregateException)
+        if (exception is AggregateException aggException)
         {
-            var aggException = exception as AggregateException;
             if (aggException.InnerExceptions.IsNullOrEmpty())
             {
                 return;
@@ -289,7 +285,7 @@ public class DefaultExceptionToErrorInfoConverter : IExceptionToErrorInfoConvert
 
         foreach (var validationResult in validationException.ValidationErrors)
         {
-            var validationError = new RemoteServiceValidationErrorInfo(validationResult.ErrorMessage);
+            var validationError = new RemoteServiceValidationErrorInfo(validationResult.ErrorMessage!);
 
             if (validationResult.MemberNames != null && validationResult.MemberNames.Any())
             {
diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/IExceptionToErrorInfoConverter.cs b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/IExceptionToErrorInfoConverter.cs
index ebf8993bd6..bd14010db0 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/IExceptionToErrorInfoConverter.cs
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/AspNetCore/ExceptionHandling/IExceptionToErrorInfoConverter.cs
@@ -24,5 +24,5 @@ public interface IExceptionToErrorInfoConverter
     /// <param name="exception">The exception.</param>
     /// <param name="options">Additional options.</param>
     /// <returns>Error info or null</returns>
-    RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions> options = null);
+    RemoteServiceErrorInfo Convert(Exception exception, Action<AbpExceptionHandlingOptions>? options = null);
 }
diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Domain/Entities/EntityNotFoundException.cs b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Domain/Entities/EntityNotFoundException.cs
index 1feb8c4cbb..5f524f9578 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Domain/Entities/EntityNotFoundException.cs
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Domain/Entities/EntityNotFoundException.cs
@@ -10,12 +10,12 @@ public class EntityNotFoundException : AbpException
     /// <summary>
     /// Type of the entity.
     /// </summary>
-    public Type EntityType { get; set; }
+    public Type? EntityType { get; set; }
 
     /// <summary>
     /// Id of the Entity.
     /// </summary>
-    public object Id { get; set; }
+    public object? Id { get; set; }
 
     /// <summary>
     /// Creates a new <see cref="EntityNotFoundException"/> object.
@@ -37,7 +37,7 @@ public class EntityNotFoundException : AbpException
     /// <summary>
     /// Creates a new <see cref="EntityNotFoundException"/> object.
     /// </summary>
-    public EntityNotFoundException(Type entityType, object id)
+    public EntityNotFoundException(Type entityType, object? id)
         : this(entityType, id, null)
     {
 
@@ -46,7 +46,7 @@ public class EntityNotFoundException : AbpException
     /// <summary>
     /// Creates a new <see cref="EntityNotFoundException"/> object.
     /// </summary>
-    public EntityNotFoundException(Type entityType, object id, Exception innerException)
+    public EntityNotFoundException(Type entityType, object? id, Exception? innerException)
         : base(
             id == null
                 ? $"There is no such an entity given id. Entity type: {entityType.FullName}"
diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/Client/AbpRemoteCallException.cs b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/Client/AbpRemoteCallException.cs
index 78c5bff6f9..887c8fb081 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/Client/AbpRemoteCallException.cs
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/Client/AbpRemoteCallException.cs
@@ -9,18 +9,18 @@ public class AbpRemoteCallException : AbpException, IHasErrorCode, IHasErrorDeta
 {
     public int HttpStatusCode { get; set; }
 
-    public string Code => Error?.Code;
+    public string? Code => Error?.Code;
 
-    public string Details => Error?.Details;
+    public string? Details => Error?.Details;
 
-    public RemoteServiceErrorInfo Error { get; set; }
+    public RemoteServiceErrorInfo? Error { get; set; }
 
     public AbpRemoteCallException()
     {
 
     }
 
-    public AbpRemoteCallException(string message, Exception innerException = null)
+    public AbpRemoteCallException(string message, Exception? innerException = null)
         : base(message, innerException)
     {
 
@@ -32,7 +32,7 @@ public class AbpRemoteCallException : AbpException, IHasErrorCode, IHasErrorDeta
 
     }
 
-    public AbpRemoteCallException(RemoteServiceErrorInfo error, Exception innerException = null)
+    public AbpRemoteCallException(RemoteServiceErrorInfo error, Exception? innerException = null)
         : base(error.Message, innerException)
     {
         Error = error;
diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceErrorInfo.cs b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceErrorInfo.cs
index 89ed87454a..e61d55e2d3 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceErrorInfo.cs
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceErrorInfo.cs
@@ -12,27 +12,27 @@ public class RemoteServiceErrorInfo
     /// <summary>
     /// Error code.
     /// </summary>
-    public string Code { get; set; }
+    public string? Code { get; set; }
 
     /// <summary>
     /// Error message.
     /// </summary>
-    public string Message { get; set; }
+    public string? Message { get; set; }
 
     /// <summary>
     /// Error details.
     /// </summary>
-    public string Details { get; set; }
+    public string? Details { get; set; }
 
     /// <summary>
     /// Error data.
     /// </summary>
-    public IDictionary Data { get; set; }
+    public IDictionary? Data { get; set; }
 
     /// <summary>
     /// Validation errors if exists.
     /// </summary>
-    public RemoteServiceValidationErrorInfo[] ValidationErrors { get; set; }
+    public RemoteServiceValidationErrorInfo[]? ValidationErrors { get; set; }
 
     /// <summary>
     /// Creates a new instance of <see cref="RemoteServiceErrorInfo"/>.
@@ -49,7 +49,7 @@ public class RemoteServiceErrorInfo
     /// <param name="details">Error details</param>
     /// <param name="message">Error message</param>
     /// <param name="data">Error data</param>
-    public RemoteServiceErrorInfo(string message, string details = null, string code = null, IDictionary data = null)
+    public RemoteServiceErrorInfo(string message, string? details = null, string? code = null, IDictionary? data = null)
     {
         Message = message;
         Details = details;
diff --git a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceValidationErrorInfo.cs b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceValidationErrorInfo.cs
index 4b86bbf4e3..64a31d7041 100644
--- a/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceValidationErrorInfo.cs
+++ b/framework/src/Volo.Abp.ExceptionHandling/Volo/Abp/Http/RemoteServiceValidationErrorInfo.cs
@@ -11,12 +11,12 @@ public class RemoteServiceValidationErrorInfo
     /// <summary>
     /// Validation error message.
     /// </summary>
-    public string Message { get; set; }
+    public string Message { get; set; } = default!;
 
     /// <summary>
     /// Relate invalid members (fields/properties).
     /// </summary>
-    public string[] Members { get; set; }
+    public string[] Members { get; set; } = default!;
 
     /// <summary>
     /// Creates a new instance of <see cref="RemoteServiceValidationErrorInfo"/>.