CODEWITHSUNDEEP
c#asp.netasp.net-mvcasp.net-mvc-4razor
SBirthare
SBirthare

Reputation: 5137

Who is invoking Error view and why?

I got a MVC4 web application running and functioning properly since almost a year. Lately while reviewing production error logs, I found a lot of mysterious exception entries of same type. I checked logs and found these exceptions occur on both Beta and Production environment but not in local (seems like a hint - see findings 1 below).

There are two subsequent entries:

One is:

Thread Id: 56, Message: Server_Exception - The view 'Error' or its master was not found or no view engine supports the searched locations. The following locations were searched: ~/Views/OrganizationUser/Error.cshtml ~/Views/OrganizationUser/Error.vbhtml ~/Views/Shared/Error.cshtml ~/Views/Shared/Error.vbhtml

Second log entry is:

Thread Id: 56, Message: Server_Exception - Stack Trace - at System.Web.Mvc.ViewResult.FindView(ControllerContext context) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.b__22(IAsyncResult asyncResult) at System.Web.Mvc.Controller.<>c__DisplayClass1d.b__18(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.b__3(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

The exception is logged from Application_Error() in global.asax.cs like so:

            var ex = Server.GetLastError();

            if (ex != null)
            {
                logger.Log(string.Format("Server_Exception - {0}", ex.Message), LogCategory.Error);
                logger.Log(string.Format("Server_Exception - Stack Trace - {0}", ex.StackTrace), LogCategory.Error);
            }

And here is the snapshot of DB log messages:

enter image description here

Finding/Analysis:

  1. Since the errors are logged only on remote server, it tells me it has got to do with how MVC handles remote errors? CustomErrors? - I don't have it defined it in web.config. Should I?

  2. But the main question is, what caused the error to happen? And who is looking for view name Error? I know its hard for you to guess it but just checking my luck.

  3. Another finding is the exceptions are logged after user has logged out. In my Login get form, I check isAuthenticated and if user is not authenticated I log a message 'Request not authenticated, showing login form.' and display login form. I can see this message in logged prior to above exception messages. So what's going on on login.cshtml that causes a contact to server which generates an error? I checked, login page and _Layout which has lots of server side code embedded but could not figure out what could cause server to try to load Error page.

I think internally MVC is calling Error page which does not exist in my source code hence these exception. But why 'Error' page? I thought to get advice on what to check in this case. Please advise if you want me to share anything that could help you understand my problem.

Upvotes: 1

Views: 1711

Answers (1)

Russ Cam
Russ Cam

Reputation: 125498

I suspect you are using the System.Web.Mvc.HandleErrorAttribute as this attribute will attempt to look for an Error view under certain conditions when an exception is thrown inside a controller action:

  1. The currently executing action is not a child action
  2. The exception has not already been handled or custom errors are enabled
  3. When wrapped in a HttpException, the exception has a 500 HTTP status code
  4. The exception is an instance of System.Exception

When all of the above are true, System.Web.Mvc.HandleErrorAttribute creates a System.Web.Mvc.HandleErrorInfo instance, sets the ExceptionContext.Result property to a ViewResult which by default has the ViewName property set to Error.

Putting all of this together, In one of your controllers, an exception must be being thrown that meets all of the above points, in a controller action that has the [HandleError] attribute applied (maybe it's applied globally), which is attempting to find the Error view and failing to do so.

To know what the original exception is, you could put an Error view into your solution and write out the Exception message of the HandleErrorInfo model instance passed to the view (if the current user has the appropriate access controls).

Upvotes: 3

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