Question

我正在Microsoft Visual Studio社区2017中处理ASP.NET示例项目。我目前正在处理的项目昨天运行良好。当我今天打开项目时，我立即收到一个消息框：

项目系统遇到错误。

具有相同键但具有不同值的元素已存在。密钥：Microsoft.EntityFrameworkCore.InMemory

已写入诊断日志：

=====================
Crippling
System.AggregateException: One or more errors occurred. ---> System.ArgumentException: An element with the same key but a different value already exists. Key: Microsoft.EntityFrameworkCore.InMemory
   at System.Collections.Immutable.ImmutableDictionary`2.HashBucket.Add(TKey key, TValue value, IEqualityComparer`1 keyOnlyComparer, IEqualityComparer`1 valueComparer, KeyCollisionBehavior behavior, OperationResult& result)
   at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 items, MutationInput origin, KeyCollisionBehavior collisionBehavior)
   at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 pairs, Boolean avoidToHashMap)
   at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 pairs)
   at Microsoft.VisualStudio.ProjectSystem.Designers.ProjectBuildSubscriptionService.UpdateRuleSnapshotCore(IProjectVersionedValue`1 source, String ruleName, IRule rule, ImmutableDictionary`2 items, ImmutableDictionary`2 properties, ImmutableList`1 recentItemRenames, IProjectChangeDiff& diff)
   at Microsoft.VisualStudio.ProjectSystem.Designers.ProjectRuleSubscriptionServiceBase`1.UpdateSnapshotCoreAsync(TSource source, IImmutableSet`1 subscribedElements, IProjectVersionedValue`1 previousResult)
   at Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase`3.<UpdateSnapshotAsync>d__28.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase`3.<>c__DisplayClass27_0.<<Initialize>b__1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Threading.JoinableTask.<JoinAsync>d__76.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Threading.JoinableTask`1.<JoinAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase`3.<<Initialize>b__27_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.DataflowExtensions.<>c__DisplayClass23_0`2.<<CreateSelfFilteringTransformBlock>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.VisualStudio.ProjectSystem.CommonProjectSystemTools.Rethrow(Exception ex)
   at Microsoft.VisualStudio.ProjectSystem.ProjectErrorReporting.<>c__DisplayClass6_0.<SubmitErrorReport>b__0()
   at Microsoft.VisualStudio.ProjectSystem.ExceptionFilter.<>c__DisplayClass2_0.<Guard>b__0()
   at GuardMethodClass.GuardMethod(Func`1 , Func`2 , Func`2 )
   --- End of inner exception stack trace ---
---> (Inner Exception #0) System.ArgumentException: An element with the same key but a different value already exists. Key: Microsoft.EntityFrameworkCore.InMemory
   at System.Collections.Immutable.ImmutableDictionary`2.HashBucket.Add(TKey key, TValue value, IEqualityComparer`1 keyOnlyComparer, IEqualityComparer`1 valueComparer, KeyCollisionBehavior behavior, OperationResult& result)
   at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 items, MutationInput origin, KeyCollisionBehavior collisionBehavior)
   at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 pairs, Boolean avoidToHashMap)
   at System.Collections.Immutable.ImmutableDictionary`2.AddRange(IEnumerable`1 pairs)
   at Microsoft.VisualStudio.ProjectSystem.Designers.ProjectBuildSubscriptionService.UpdateRuleSnapshotCore(IProjectVersionedValue`1 source, String ruleName, IRule rule, ImmutableDictionary`2 items, ImmutableDictionary`2 properties, ImmutableList`1 recentItemRenames, IProjectChangeDiff& diff)
   at Microsoft.VisualStudio.ProjectSystem.Designers.ProjectRuleSubscriptionServiceBase`1.UpdateSnapshotCoreAsync(TSource source, IImmutableSet`1 subscribedElements, IProjectVersionedValue`1 previousResult)
   at Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase`3.<UpdateSnapshotAsync>d__28.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase`3.<>c__DisplayClass27_0.<<Initialize>b__1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Threading.JoinableTask.<JoinAsync>d__76.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Threading.JoinableTask`1.<JoinAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.Designers.CustomizableBlockSubscriberBase`3.<<Initialize>b__27_0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.ProjectSystem.DataflowExtensions.<>c__DisplayClass23_0`2.<<CreateSelfFilteringTransformBlock>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.VisualStudio.ProjectSystem.CommonProjectSystemTools.Rethrow(Exception ex)
   at Microsoft.VisualStudio.ProjectSystem.ProjectErrorReporting.<>c__DisplayClass6_0.<SubmitErrorReport>b__0()
   at Microsoft.VisualStudio.ProjectSystem.ExceptionFilter.<>c__DisplayClass2_0.<Guard>b__0()
   at GuardMethodClass.GuardMethod(Func`1 , Func`2 , Func`2 )<---

===================

它还导致了一些其他问题，例如我对System和Microsoft命名空间的所有使用指令都出错：

可以找到类型或命名空间名称'System'（您是否缺少using指令或程序集引用？）

由于这些指令对其他项目仍然有效，我怀疑它们会在修复EntityFramework问题时消退。

我尝试重新启动Visual Studio和我的计算机，并尝试构建项目。我无法添加对项目的引用。我收到了消息框：

任务已取消

无法完成操作

对项目中名称空间的引用仍然正常。

感谢您的帮助。

Answer 1

关闭VS。
通过以下方式打开项目文件（csproj文件或project.json）外部文本编辑器并删除重复的包引用。
重新打开VS.一切都应该正常。

如果使用csproj文件格式 - 请查找以下行：

<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="1.1.1" />

EntityFrameworkCore.InMemory System.ArgumentException

1 个答案: