Question

I am new to aspx webforms.

I want to catch a specific Exception in my Web Application – Validation of viewstate MAC failed.
I tried this (in Global.asax.cs):

protected void Application_Error(object sender, EventArgs e)
{
  HttpException lastErrWrapper = Server.GetLastError() as HttpException;

  if ((uint)lastErrWrapper.ErrorCode == 0x80004005)
  {
      // do something
  }         
}

The problem is that it catches all unhandled HttpExceptions.

What is the best way to achieve this ?

---

edit:

While checking this issue further I found that the inner exception is a ViewStateException, but it doesn’t seem to have a specific “errorCode” attribute

Thanks

Answer 1

This should do it

if ((lastErrWrapper != null) && (lastErrWrapper.InnerException != null) 
  && (lastErrWrapper.InnerException is ViewStateException)
{
}

The HttpException is designed to make all the HTTP/web related stuff be catchable by one handler, so you need to dig in and look at the original exception. ViewStateException might catch a couple of other View State-related errors, but that’s probably OK.