Fix: Random FileNotFoundException in ASP.Net 2.0 application

Issue  -  Random FileNotFoundException when browsing ASP.Net 2.0 application.  An event similar to the following will be logged in the event viewer.  The file name in the exception is typically different every time:

Exception message: Could not load file or assembly 'App_Web_-a8debde, Version=, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.

  Stack trace:    at ASP.UserControl_ascx.__BuildControlmain()
   at ASP.UserControl_ascx.__BuildControlTree(dynamic_default_ascx __ctrl)
   at ASP.UserControl_ascx.FrameworkInitialize()
   at System.Web.UI.UserControl.InitializeAsUserControlInternal()
   at System.Web.UI.UserControl.InitializeAsUserControl(Page page)
   at ASP.default_aspx.__BuildControlhtml_content()
   at ASP.default_aspx.__BuildControlTree(default_aspx __ctrl)
   at ASP.default_aspx.FrameworkInitialize()
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at ASP.default_aspx.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Workarounds  -  In some cases, it's necessary to clear the Temporary ASP.Net Files folder and restart the application pool.  We've found in some cases that setting batch="false" in the web.config file will resolve the issue as well, however, there are some perf reasons for not doing that long term in production.

Getting the Fix  -  The KB for this fix is not yet public (I'll link it as soon as it is), however, the fix is available.  You will need to contact Microsoft Support ( and ask for the fix from KB article 934839.