Question

I’m writing an upload function, and have problems catching ‘System.Web.HttpException: Maximum request length exceeded’ with files larger than the specified max size in httpRuntimein web.config (max size set to 5120). I’m using a simple <input> for the file.

The problem is that the exception is thrown before the upload button’s click-event, and the exception happens before my code is run. So how do I catch and handle the exception?

EDIT: The exception is thrown instantly, so I’m pretty sure it’s not a timeout issue due to slow connections.

Answer 1

There is no easy way to catch such exception unfortunately. What I do is either override the OnError method at the page level or the Application_Error in global.asax, then check if it was a Max Request failure and, if so, transfer to an error page.

protected override void OnError(EventArgs e) .....   private void Application_Error(object sender, EventArgs e) {     if (GlobalHelper.IsMaxRequestExceededException(this.Server.GetLastError()))     {         this.Server.ClearError();         this.Server.Transfer('~/error/UploadTooLarge.aspx');     } } 

It’s a hack but the code below works for me

const int TimedOutExceptionCode = -2147467259; public static bool IsMaxRequestExceededException(Exception e) {     // unhandled errors = caught at global.ascx level     // http exception = caught at page level      Exception main;     var unhandled = e as HttpUnhandledException;      if (unhandled != null && unhandled.ErrorCode == TimedOutExceptionCode)     {         main = unhandled.InnerException;     }     else     {         main = e;     }       var http = main as HttpException;      if (http != null && http.ErrorCode == TimedOutExceptionCode)     {         // hack: no real method of identifying if the error is max request exceeded as          // it is treated as a timeout exception         if (http.StackTrace.Contains('GetEntireRawContent'))         {             // MAX REQUEST HAS BEEN EXCEEDED             return true;         }     }      return false; }