diff --git a/framework/src/Volo.Abp.Core/Volo.Abp.Core.csproj b/framework/src/Volo.Abp.Core/Volo.Abp.Core.csproj
index 6d6164a86d..8ef5624f04 100644
--- a/framework/src/Volo.Abp.Core/Volo.Abp.Core.csproj
+++ b/framework/src/Volo.Abp.Core/Volo.Abp.Core.csproj
@@ -1,7 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
-
   <Import Project="..\..\..\common.props" />
-
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyName>Volo.Abp.Core</AssemblyName>
@@ -12,7 +10,6 @@
     <GenerateAssemblyProductAttribute>false</GenerateAssemblyProductAttribute>
     <RootNamespace />
   </PropertyGroup>
-
   <ItemGroup>
     <PackageReference Include="System.ComponentModel.Annotations" Version="4.5.0" />
     <PackageReference Include="System.Collections.Immutable" Version="1.5.0" />
@@ -28,5 +25,4 @@
     <PackageReference Include="Nito.AsyncEx.Coordination" Version="1.0.2" />
     <PackageReference Include="Nito.AsyncEx.Context" Version="1.1.0" />
   </ItemGroup>
-
-</Project>
+</Project>
\ No newline at end of file
diff --git a/framework/src/Volo.Abp.Core/Volo/Abp/UI/IUserFriendlyException.cs b/framework/src/Volo.Abp.Core/Volo/Abp/IUserFriendlyException.cs
similarity index 55%
rename from framework/src/Volo.Abp.Core/Volo/Abp/UI/IUserFriendlyException.cs
rename to framework/src/Volo.Abp.Core/Volo/Abp/IUserFriendlyException.cs
index d2a75e1d25..a3a45dbfc2 100644
--- a/framework/src/Volo.Abp.Core/Volo/Abp/UI/IUserFriendlyException.cs
+++ b/framework/src/Volo.Abp.Core/Volo/Abp/IUserFriendlyException.cs
@@ -1,7 +1,5 @@
-namespace Volo.Abp.UI
+namespace Volo.Abp
 {
-    //TODO: Move to Volo.Abp namespace
-
     public interface IUserFriendlyException : IBusinessException
     {
 
diff --git a/framework/src/Volo.Abp.Core/Volo/Abp/UI/UserFriendlyException.cs b/framework/src/Volo.Abp.Core/Volo/Abp/UserFriendlyException.cs
similarity index 94%
rename from framework/src/Volo.Abp.Core/Volo/Abp/UI/UserFriendlyException.cs
rename to framework/src/Volo.Abp.Core/Volo/Abp/UserFriendlyException.cs
index 54fc7fd091..0dac2c8fe3 100644
--- a/framework/src/Volo.Abp.Core/Volo/Abp/UI/UserFriendlyException.cs
+++ b/framework/src/Volo.Abp.Core/Volo/Abp/UserFriendlyException.cs
@@ -2,10 +2,8 @@ using System;
 using System.Runtime.Serialization;
 using Microsoft.Extensions.Logging;
 
-namespace Volo.Abp.UI
+namespace Volo.Abp
 {
-    //TODO: Move to Volo.Abp namespace
-
     /// <summary>
     /// This exception type is directly shown to the user.
     /// </summary>
diff --git a/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/App/Views/Simple/ExceptionOnRazor.cshtml b/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/App/Views/Simple/ExceptionOnRazor.cshtml
index 65a222e6f5..ec7bee0ca6 100644
--- a/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/App/Views/Simple/ExceptionOnRazor.cshtml
+++ b/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/App/Views/Simple/ExceptionOnRazor.cshtml
@@ -1,4 +1,4 @@
-@using Volo.Abp.UI
+@using Volo.Abp
 <h2>Exception test</h2>
 @{
     throw new UserFriendlyException("test exception!");
diff --git a/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController.cs b/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController.cs
index 16a9fd9c11..8ada2e03d0 100644
--- a/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController.cs
+++ b/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController.cs
@@ -1,5 +1,4 @@
 using Microsoft.AspNetCore.Mvc;
-using Volo.Abp.UI;
 
 namespace Volo.Abp.AspNetCore.Mvc.ExceptionHandling
 {
diff --git a/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController_Tests.cs b/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController_Tests.cs
index e48c3883ef..5243307116 100644
--- a/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController_Tests.cs
+++ b/framework/test/Volo.Abp.AspNetCore.Mvc.Tests/Volo/Abp/AspNetCore/Mvc/ExceptionHandling/ExceptionTestController_Tests.cs
@@ -2,7 +2,6 @@
 using System.Threading.Tasks;
 using Shouldly;
 using Volo.Abp.Http;
-using Volo.Abp.UI;
 using Xunit;
 
 namespace Volo.Abp.AspNetCore.Mvc.ExceptionHandling