Problem:

When debugging asp.net by attaching w3wp.exe process, you often will see encounter the following error message, the web server process that was being debugged has been terminated by IIS.

Analysis:

This caused Internet Information Services (IIS) to assume that the worker process had stopped responding. Therefore, IIS terminated the worker process.

Solution:

1. Open IIS manager.

2.Click application Pools>>select the application pool associated with the site>>and click Advanced Settings

3. Click Advanced Settings of the application pool and set the Ping Enabled property from True to False.

Now, reattach the process from Visual Studio, you should not get the error message.

References:

msdn