“/”应用程序中的服务器错误。

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[InvalidOperationException: 序列不包含任何匹配元素]
   System.Linq.Enumerable.First(IEnumerable`1 source, Func`2 predicate) +482
   Mammothcode.DeMa.web.Controllers.HomeController.ProblemFeedbackDetails(String id, String roleId) in C:\Users\yc\Desktop\德玛代码最新\Mammothcode.Dema\Mammothcode.Dema\Mammothcode.DeMa.web\Controllers\HomeController.cs:195
   lambda_method(Closure , ControllerBase , Object[] ) +179
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +274
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +39
   System.Web.Mvc.Async.<>c__DisplayClass39.b__33() +120
   System.Web.Mvc.Async.<>c__DisplayClass4f.b__49() +452
   System.Web.Mvc.Async.<>c__DisplayClass37.b__36(IAsyncResult asyncResult) +15
   System.Web.Mvc.Async.<>c__DisplayClass2a.b__20() +33
   System.Web.Mvc.Async.<>c__DisplayClass25.b__22(IAsyncResult asyncResult) +240
   System.Web.Mvc.<>c__DisplayClass1d.b__18(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.<>c__DisplayClass4.b__3(IAsyncResult ar) +15
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +53
   System.Web.Mvc.Async.<>c__DisplayClass4.b__3(IAsyncResult ar) +15
   System.Web.Mvc.<>c__DisplayClass8.b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass4.b__3(IAsyncResult ar) +15
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +606
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288