diff --git a/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantConfigurationProvider.cs b/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantConfigurationProvider.cs
index 7bc34a4d8e..d8889da315 100644
--- a/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantConfigurationProvider.cs
+++ b/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantConfigurationProvider.cs
@@ -4,5 +4,5 @@ namespace Volo.Abp.MultiTenancy;
 
 public interface ITenantConfigurationProvider
 {
-    Task<TenantConfiguration> GetAsync(bool saveResolveResult = false);
+    Task<TenantConfiguration?> GetAsync(bool saveResolveResult = false);
 }
diff --git a/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantResolveResultAccessor.cs b/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantResolveResultAccessor.cs
index 9123910167..707b59493b 100644
--- a/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantResolveResultAccessor.cs
+++ b/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantResolveResultAccessor.cs
@@ -4,6 +4,5 @@ namespace Volo.Abp.MultiTenancy;
 
 public interface ITenantResolveResultAccessor
 {
-    [CanBeNull]
-    TenantResolveResult Result { get; set; }
+    TenantResolveResult? Result { get; set; }
 }
diff --git a/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantStore.cs b/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantStore.cs
index ec2f79f9c4..93dd609cc4 100644
--- a/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantStore.cs
+++ b/framework/src/Volo.Abp.MultiTenancy.Abstractions/Volo/Abp/MultiTenancy/ITenantStore.cs
@@ -5,13 +5,13 @@ namespace Volo.Abp.MultiTenancy;
 
 public interface ITenantStore
 {
-    Task<TenantConfiguration> FindAsync(string name);
+    Task<TenantConfiguration?> FindAsync(string name);
 
-    Task<TenantConfiguration> FindAsync(Guid id);
+    Task<TenantConfiguration?> FindAsync(Guid id);
 
     [Obsolete("Use FindAsync method.")]
-    TenantConfiguration Find(string name);
+    TenantConfiguration? Find(string name);
 
     [Obsolete("Use FindAsync method.")]
-    TenantConfiguration Find(Guid id);
+    TenantConfiguration? Find(Guid id);
 }
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo.Abp.MultiTenancy.csproj b/framework/src/Volo.Abp.MultiTenancy/Volo.Abp.MultiTenancy.csproj
index e2a247ffd4..30d1a1c9a0 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo.Abp.MultiTenancy.csproj
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo.Abp.MultiTenancy.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.MultiTenancy</AssemblyName>
     <PackageId>Volo.Abp.MultiTenancy</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/AsyncLocalCurrentTenantAccessor.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/AsyncLocalCurrentTenantAccessor.cs
index 8d04f0eafe..595aaa0f10 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/AsyncLocalCurrentTenantAccessor.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/AsyncLocalCurrentTenantAccessor.cs
@@ -7,15 +7,15 @@ public class AsyncLocalCurrentTenantAccessor : ICurrentTenantAccessor
 {
     public static AsyncLocalCurrentTenantAccessor Instance { get; } = new();
 
-    public BasicTenantInfo Current {
+    public BasicTenantInfo? Current {
         get => _currentScope.Value;
         set => _currentScope.Value = value;
     }
 
-    private readonly AsyncLocal<BasicTenantInfo> _currentScope;
+    private readonly AsyncLocal<BasicTenantInfo?> _currentScope;
 
     private AsyncLocalCurrentTenantAccessor()
     {
-        _currentScope = new AsyncLocal<BasicTenantInfo>();
+        _currentScope = new AsyncLocal<BasicTenantInfo?>();
     }
 }
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/ConfigurationStore/DefaultTenantStore.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/ConfigurationStore/DefaultTenantStore.cs
index aa7eeb3a8a..d86d810d11 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/ConfigurationStore/DefaultTenantStore.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/ConfigurationStore/DefaultTenantStore.cs
@@ -16,22 +16,22 @@ public class DefaultTenantStore : ITenantStore, ITransientDependency
         _options = options.CurrentValue;
     }
 
-    public Task<TenantConfiguration> FindAsync(string name)
+    public Task<TenantConfiguration?> FindAsync(string name)
     {
         return Task.FromResult(Find(name));
     }
 
-    public Task<TenantConfiguration> FindAsync(Guid id)
+    public Task<TenantConfiguration?> FindAsync(Guid id)
     {
         return Task.FromResult(Find(id));
     }
 
-    public TenantConfiguration Find(string name)
+    public TenantConfiguration? Find(string name)
     {
         return _options.Tenants?.FirstOrDefault(t => t.Name == name);
     }
 
-    public TenantConfiguration Find(Guid id)
+    public TenantConfiguration? Find(Guid id)
     {
         return _options.Tenants?.FirstOrDefault(t => t.Id == id);
     }
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/CurrentTenant.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/CurrentTenant.cs
index fb5d2b147c..1e0bb380dc 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/CurrentTenant.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/CurrentTenant.cs
@@ -9,7 +9,7 @@ public class CurrentTenant : ICurrentTenant, ITransientDependency
 
     public virtual Guid? Id => _currentTenantAccessor.Current?.TenantId;
 
-    public string Name => _currentTenantAccessor.Current?.Name;
+    public string? Name => _currentTenantAccessor.Current?.Name;
 
     private readonly ICurrentTenantAccessor _currentTenantAccessor;
 
@@ -18,17 +18,17 @@ public class CurrentTenant : ICurrentTenant, ITransientDependency
         _currentTenantAccessor = currentTenantAccessor;
     }
 
-    public IDisposable Change(Guid? id, string name = null)
+    public IDisposable Change(Guid? id, string? name = null)
     {
         return SetCurrent(id, name);
     }
 
-    private IDisposable SetCurrent(Guid? tenantId, string name = null)
+    private IDisposable SetCurrent(Guid? tenantId, string? name = null)
     {
         var parentScope = _currentTenantAccessor.Current;
         _currentTenantAccessor.Current = new BasicTenantInfo(tenantId, name);
 
-        return new DisposeAction<ValueTuple<ICurrentTenantAccessor, BasicTenantInfo>>(static (state) =>
+        return new DisposeAction<ValueTuple<ICurrentTenantAccessor, BasicTenantInfo?>>(static (state) =>
         {
             var (currentTenantAccessor, parentScope) = state;
             currentTenantAccessor.Current = parentScope;
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/MultiTenantConnectionStringResolver.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/MultiTenantConnectionStringResolver.cs
index b5c01170c5..6ed12a3159 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/MultiTenantConnectionStringResolver.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/MultiTenantConnectionStringResolver.cs
@@ -24,7 +24,7 @@ public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolv
         _serviceProvider = serviceProvider;
     }
 
-    public override async Task<string> ResolveAsync(string connectionStringName = null)
+    public override async Task<string> ResolveAsync(string? connectionStringName = null)
     {
         if (_currentTenant.Id == null)
         {
@@ -40,7 +40,7 @@ public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolv
             return await base.ResolveAsync(connectionStringName);
         }
 
-        var tenantDefaultConnectionString = tenant.ConnectionStrings.Default;
+        var tenantDefaultConnectionString = tenant.ConnectionStrings?.Default;
 
         //Requesting default connection string...
         if (connectionStringName == null ||
@@ -48,41 +48,41 @@ public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolv
         {
             //Return tenant's default or global default
             return !tenantDefaultConnectionString.IsNullOrWhiteSpace()
-                ? tenantDefaultConnectionString
-                : Options.ConnectionStrings.Default;
+                ? tenantDefaultConnectionString!
+                : Options.ConnectionStrings.Default!;
         }
 
         //Requesting specific connection string...
-        var connString = tenant.ConnectionStrings.GetOrDefault(connectionStringName);
+        var connString = tenant.ConnectionStrings?.GetOrDefault(connectionStringName);
         if (!connString.IsNullOrWhiteSpace())
         {
             //Found for the tenant
-            return connString;
+            return connString!;
         }
 
         //Fallback to the mapped database for the specific connection string
         var database = Options.Databases.GetMappedDatabaseOrNull(connectionStringName);
         if (database != null && database.IsUsedByTenants)
         {
-            connString = tenant.ConnectionStrings.GetOrDefault(database.DatabaseName);
+            connString = tenant.ConnectionStrings?.GetOrDefault(database.DatabaseName);
             if (!connString.IsNullOrWhiteSpace())
             {
                 //Found for the tenant
-                return connString;
+                return connString!;
             }
         }
 
         //Fallback to tenant's default connection string if available
         if (!tenantDefaultConnectionString.IsNullOrWhiteSpace())
         {
-            return tenantDefaultConnectionString;
+            return tenantDefaultConnectionString!;
         }
 
         return await base.ResolveAsync(connectionStringName);
     }
 
     [Obsolete("Use ResolveAsync method.")]
-    public override string Resolve(string connectionStringName = null)
+    public override string Resolve(string? connectionStringName = null)
     {
         if (_currentTenant.Id == null)
         {
@@ -98,7 +98,7 @@ public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolv
             return base.Resolve(connectionStringName);
         }
 
-        var tenantDefaultConnectionString = tenant.ConnectionStrings.Default;
+        var tenantDefaultConnectionString = tenant.ConnectionStrings?.Default;
 
         //Requesting default connection string...
         if (connectionStringName == null ||
@@ -106,42 +106,42 @@ public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolv
         {
             //Return tenant's default or global default
             return !tenantDefaultConnectionString.IsNullOrWhiteSpace()
-                ? tenantDefaultConnectionString
-                : Options.ConnectionStrings.Default;
+                ? tenantDefaultConnectionString!
+                : Options.ConnectionStrings.Default!;
         }
 
         //Requesting specific connection string...
-        var connString = tenant.ConnectionStrings.GetOrDefault(connectionStringName);
+        var connString = tenant.ConnectionStrings?.GetOrDefault(connectionStringName);
         if (!connString.IsNullOrWhiteSpace())
         {
             //Found for the tenant
-            return connString;
+            return connString!;
         }
 
         //Fallback to tenant's default connection string if available
         if (!tenantDefaultConnectionString.IsNullOrWhiteSpace())
         {
-            return tenantDefaultConnectionString;
+            return tenantDefaultConnectionString!;
         }
 
         //Try to find the specific connection string for given name
         var connStringInOptions = Options.ConnectionStrings.GetOrDefault(connectionStringName);
         if (!connStringInOptions.IsNullOrWhiteSpace())
         {
-            return connStringInOptions;
+            return connStringInOptions!;
         }
 
         //Fallback to the global default connection string
         var defaultConnectionString = Options.ConnectionStrings.Default;
         if (!defaultConnectionString.IsNullOrWhiteSpace())
         {
-            return defaultConnectionString;
+            return defaultConnectionString!;
         }
 
         throw new AbpException("No connection string defined!");
     }
 
-    protected virtual async Task<TenantConfiguration> FindTenantConfigurationAsync(Guid tenantId)
+    protected virtual async Task<TenantConfiguration?> FindTenantConfigurationAsync(Guid tenantId)
     {
         using (var serviceScope = _serviceProvider.CreateScope())
         {
@@ -154,7 +154,7 @@ public class MultiTenantConnectionStringResolver : DefaultConnectionStringResolv
     }
 
     [Obsolete("Use FindTenantConfigurationAsync method.")]
-    protected virtual TenantConfiguration FindTenantConfiguration(Guid tenantId)
+    protected virtual TenantConfiguration? FindTenantConfiguration(Guid tenantId)
     {
         using (var serviceScope = _serviceProvider.CreateScope())
         {
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/NullTenantResolveResultAccessor.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/NullTenantResolveResultAccessor.cs
index 023617d405..424d9ea8b8 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/NullTenantResolveResultAccessor.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/NullTenantResolveResultAccessor.cs
@@ -4,7 +4,7 @@ namespace Volo.Abp.MultiTenancy;
 
 public class NullTenantResolveResultAccessor : ITenantResolveResultAccessor, ISingletonDependency
 {
-    public TenantResolveResult Result {
+    public TenantResolveResult? Result {
         get => null;
         set { }
     }
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantConfigurationProvider.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantConfigurationProvider.cs
index 7df558f9f3..7e93cf888a 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantConfigurationProvider.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantConfigurationProvider.cs
@@ -25,7 +25,7 @@ public class TenantConfigurationProvider : ITenantConfigurationProvider, ITransi
         StringLocalizer = stringLocalizer;
     }
 
-    public virtual async Task<TenantConfiguration> GetAsync(bool saveResolveResult = false)
+    public virtual async Task<TenantConfiguration?> GetAsync(bool saveResolveResult = false)
     {
         var resolveResult = await TenantResolver.ResolveTenantIdOrNameAsync();
 
@@ -34,7 +34,7 @@ public class TenantConfigurationProvider : ITenantConfigurationProvider, ITransi
             TenantResolveResultAccessor.Result = resolveResult;
         }
 
-        TenantConfiguration tenant = null;
+        TenantConfiguration? tenant = null;
         if (resolveResult.TenantIdOrName != null)
         {
             tenant = await FindTenantAsync(resolveResult.TenantIdOrName);
@@ -61,7 +61,7 @@ public class TenantConfigurationProvider : ITenantConfigurationProvider, ITransi
         return tenant;
     }
 
-    protected virtual async Task<TenantConfiguration> FindTenantAsync(string tenantIdOrName)
+    protected virtual async Task<TenantConfiguration?> FindTenantAsync(string tenantIdOrName)
     {
         if (Guid.TryParse(tenantIdOrName, out var parsedTenantId))
         {
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantResolveContext.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantResolveContext.cs
index 86b0586c56..bc661f42c4 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantResolveContext.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantResolveContext.cs
@@ -6,7 +6,7 @@ public class TenantResolveContext : ITenantResolveContext
 {
     public IServiceProvider ServiceProvider { get; }
 
-    public string TenantIdOrName { get; set; }
+    public string? TenantIdOrName { get; set; }
 
     public bool Handled { get; set; }
 
diff --git a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantSettingValueProvider.cs b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantSettingValueProvider.cs
index 39c7803d52..3d672044f3 100644
--- a/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantSettingValueProvider.cs
+++ b/framework/src/Volo.Abp.MultiTenancy/Volo/Abp/MultiTenancy/TenantSettingValueProvider.cs
@@ -19,7 +19,7 @@ public class TenantSettingValueProvider : SettingValueProvider
         CurrentTenant = currentTenant;
     }
 
-    public async override Task<string> GetOrNullAsync(SettingDefinition setting)
+    public async override Task<string?> GetOrNullAsync(SettingDefinition setting)
     {
         return await SettingStore.GetOrNullAsync(setting.Name, Name, CurrentTenant.Id?.ToString());
     }