Can't understand why I'm getting this nullReference exception in ASP MVC when loading a page

Question

I have a web application that is not giving me any problems on my computer, but when I deploy it to the server I get this error. It doesn't give me any source code lines to check and I don't have any idea why it may be happening

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 


[No relevant source lines]

Source File: c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\a9dc635c\ccb3814\App_Web_item.cshtml.f0356b3c.uyw8roer.0.cs    Line: 0 

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.]
   ASP._Page__AssemblyResource_MyProject_Web_Mvc__Version_1_0_0_0__Culture_neutral__PublicKeyToken_null_Views_LeagueGlobal_Item_cshtml.Execute() in c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\a9dc635c\ccb3814\App_Web_item.cshtml.f0356b3c.uyw8roer.0.cs:0
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +279
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +125
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +195
   System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +383
   System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +32
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +977396
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +977396
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +265
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +964636
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +20
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +67
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +20
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +53
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +20
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +53
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +469
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +375

Answer 1

I run into the same issue. Unfortunately the stack trace isn't very helpful in this case. The exception is happening for sure in the view, what it was in my case:

@Model.SomeProperty.Trim()

And Model.SomeProperty was null. As there is no way how to debug it; I recommend binary split approach:

• save your view somewhere else
• remove one-by-one logical parts from your view
• after each removal save your view and retest
• if the exception is no longer reproducible, the NullReferenceException happened in the block you've removed; so add it back and remove logical parts inside this block until you isolate the line causing an exception

Its lame I know, but I found no other way - btw. this is what I got for doing controller job in view.

Answer 2

Go to line 0 of your source file at:

c:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\a9dc635c\ccb3814\App_Web_item.cshtml.f0356b3c.uyw8roer.0.cs

Then, use this to pin-point where exactly the exception happens in your code block:

try
{
   ...
}
catch (NullReferenceException ex)
{
      ShowMessageBox("Error" + ex.Message);
}

Check that:

1. You've initiated the variables that you're manipulating.
2. Variables that you're using have not become null since deploying it to the server.
3. You are not using variables outside of your scope.