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c# - System.Threading.Tasks.Task 方法未找到

问题描述

开发应用程序并使用两台不同的机器。据我所知，它们都在同一版本的 Windows 10 (1803) 上。就在最近，我开始在一台机器上遇到问题。该应用程序使用个人帐户身份验证，并且在登录提示处，一旦用户输入他们的用户名和密码并单击登录，它就会抛出以下错误：

Method not found: 'System.Threading.Tasks.Task`1<!!0> System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(System.Linq.IQueryable`1<!!0>, System.Linq.Expressions.Expression`1<System.Func`2<!!0,Boolean>>)'.

它识别为问题的代码是（在最后一行）：

// To enable password failures to trigger account lockout, change to shouldLockout: true
//var result = await SignInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, shouldLockout: false);
var result = await SignInManager.PasswordSignInAsync(model.UserName, model.Password, model.RememberMe, shouldLockout: false); // <-- this line

我已经从可疑机器中完全删除项目并从 Git 重新克隆，但同样的问题。我浏览了我的参考资料，并与它正在使用的机器进行了比较，它们都匹配。

仅供参考，这里是堆栈跟踪：

[MissingMethodException: Method not found: 'System.Threading.Tasks.Task`1<!!0> System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(System.Linq.IQueryable`1<!!0>, System.Linq.Expressions.Expression`1<System.Func`2<!!0,Boolean>>)'.]
   Microsoft.AspNet.Identity.EntityFramework.<GetUserAggregateAsync>d__6c.MoveNext() +0
   System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.Start(TStateMachine& stateMachine) +94
   Microsoft.AspNet.Identity.EntityFramework.UserStore`6.GetUserAggregateAsync(Expression`1 filter) +146
   Microsoft.AspNet.Identity.EntityFramework.UserStore`6.FindByNameAsync(String userName) +537
   Microsoft.AspNet.Identity.UserManager`2.FindByNameAsync(String userName) +56
   Microsoft.AspNet.Identity.Owin.<PasswordSignInAsync>d__29.MoveNext() +104
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24
   CaseNotesPlus.Controllers.<Login>d__12.MoveNext() in D:\Projects\CaseNotesPlus\CaseNotesPlus\Controllers\AccountController.cs:88
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
   System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +97
   System.Web.Mvc.Async.<>c__DisplayClass8_0.<BeginInvokeAsynchronousActionMethod>b__1(IAsyncResult asyncResult) +17
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__11_0() +50
   System.Web.Mvc.Async.<>c__DisplayClass11_1.<InvokeActionMethodFilterAsynchronouslyRecursive>b__2() +228
   System.Web.Mvc.Async.<>c__DisplayClass7_0.<BeginInvokeActionMethodWithFilters>b__1(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass3_6.<BeginInvokeAction>b__3() +35
   System.Web.Mvc.Async.<>c__DisplayClass3_1.<BeginInvokeAction>b__5(IAsyncResult asyncResult) +100
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
   System.Web.Mvc.<>c.<BeginExecuteCore>b__152_1(IAsyncResult asyncResult, ExecuteCoreState innerState) +11
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +45
   System.Web.Mvc.<>c.<BeginExecute>b__151_2(IAsyncResult asyncResult, Controller controller) +13
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.<>c.<BeginProcessRequest>b__20_1(IAsyncResult asyncResult, ProcessRequestState innerState) +28
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9874329
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

我已经验证我在两台机器上都有相同的 NET Framework 设置： 版本信息：

标签： c#.netasp.net-mvcasynchronous

解决方案

确保您使用的是Entity Framework 6.2 版

我遇到了同样的问题，因为我使用的FirstOrDefaultAsync()是 EntityFramework 6.1.3 版本（6.2.0 之前）的 Linq 方法

根据有关“QueryableExtensions.FirstOrDefaultAsync()”的 Microsoft 文档： https ://docs.microsoft.com/en-us/dotnet/api/system.data.entity.queryableextensions.firstordefaultasync?view=entity-framework-6.2.0

此方法仅适用于**EntityFramework 6.2 **的版本

适用于

实体框架

6.2.0

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