Microsoft Visual Studio Error : Unable to start debugging on web server

Following image shows error message "unable to debug......", such kind of error are generally caused when the program runs in infinite loop due to coding mistake or when computer gets hang due to low configuration.

There are few steps to be done in order to solve this problem

Step 1 : Go to Task Manager and find IIS Worker, right click on it and end process

Step 2 : Open IIS ( Internet Information Services ) and go to Application pool, It is possible that some of your pool which you are using is stopped, for e.g. In image below Default App Pool is stopped.

Step 3 : Right click on the stopped pool and click start to start application pool as shown below

After doing above specified steps you will be able debug in visual studio.