Attach a process in visual studio (Debugging) visual studio C#

Open Visual studio

>Click on Debug

>Click on Attach to process

> Check the checkbox "Show processes from all users"(screenshot below)

>Select aspnet_wp.exe, w3p.exe, or w3wp.exe from the process list

>Click "Attach"

Now you can debug.

reference :- https://stackoverflow.com/questions/848987/attach-debugger-to-iis-instance