Problem:
“Unable to attach to the process. The system cannot find the file specified.”
OR
“Unable to start debugging on the web server. Attaching to a process in a different terminal server session is not supported on this computer. Try remote debugging to the machine and running the Microsoft Visual Studio Remote Debugging Monitor in the process’s session.”
Fix: Check your Local Security Policy, you need to ensure that Administrators have "Debug Programs" permission (Security Settings | Local Policies | User Rights Assignment)