How to handle Thread was being aborted Exception vb.net/C#?

Question

I've seen several questions regarding this issue but I've not found an apt answer for my issue. Initially I was using the following code after writing json in a function

            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.SuppressContent = True;
            HttpContext.Current.ApplicationInstance.CompleteRequest();

Was getting Server cannot append header after HTTP headers have been sent exception.

So I altered the code to

try {
    HttpContext.Current.Response.Write(Data);
    HttpContext.Current.Response.End();
} catch (System.Threading.ThreadAbortException exc) {
    try {
        //Sends the response buffer
        HttpContext.Current.Response.Flush();
        // Prevents any other content from being sent to the browser
        HttpContext.Current.Response.SuppressContent = true;
        //Directs the thread to finish, bypassing additional processing
        HttpContext.Current.ApplicationInstance.CompleteRequest();
    } catch (Exception ex) {
              //Log Exception
    }

}

All these code are in function(lets say) writeData() and its called by a function called CallWriteData . Now the exception has been successfully handled in WriteData() function but its throwing Thread was being aborted exception in the parent function CallWriteData .

To be honest its not a major issue in my project but it would be nice if I fix this annoying issue. Also this exception in CallWriteData not every-time(sometimes its successfully handled).

Answer 1

Finally,this helped me to handle Thread was being aborted exception,

try
{
   //Write HTTP output
    HttpContext.Current.Response.Write(Data);
}  
catch (Exception exc) {}
finally {
   try 
    {
      //stop processing the script and return the current result
      HttpContext.Current.Response.End();
     } 
   catch (Exception ex) {} 
   finally {
        //Sends the response buffer
        HttpContext.Current.Response.Flush();
        // Prevents any other content from being sent to the browser
        HttpContext.Current.Response.SuppressContent = true;
        //Directs the thread to finish, bypassing additional processing
        HttpContext.Current.ApplicationInstance.CompleteRequest();
        //Suspends the current thread
        Thread.Sleep(1);
     }
   }

if you use the following the following code instead of HttpContext.Current.Response.End() , you will get Server cannot append header after HTTP headers have been sent exception.

            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.SuppressContent = True;
            HttpContext.Current.ApplicationInstance.CompleteRequest();

Another Fix which I found is Thread.BeginCriticalRegion();

   try 
 {
    //Write HTTP output
   HttpContext.Current.Response.Write(Data);
  } catch (Exception exc) {} 
  finally {
    try {
     //Notifies a host that execution is about to enter a region of code in which the effects of a thread abort or unhandled exception might jeopardize other tasks in the application domain.
     Thread.BeginCriticalRegion();
     HttpContext.Current.Response.End();
         } catch (Exception ex) {} 
    finally {
    //Sends the response buffer
    HttpContext.Current.Response.Flush();
    // Prevents any other content from being sent to the browser
    HttpContext.Current.Response.SuppressContent = true;
    //Directs the thread to finish, bypassing additional processing
    HttpContext.Current.ApplicationInstance.CompleteRequest();
    Thread.EndCriticalRegion();
         }
   }

Now I'm a relieved man.

Answer 2

This is how IIS works. It starts a new thread for the new request. The thread does it's stuff, and when it ends the thread is aborted. Normally, this happens in the .NET plumbing and it's handles there. However, it you do something like a Server.Redirect() it'll also get aborted - in your code. Similarly with completing the request yourself as you do. IIS says "It's sent the return, so kill it." That's how it works.

(The thread is probably saved for re-use by another request, but the code just finished on it is aborted.)