Application Pool stops when started

If you are using a custom identity for and application pool and get either of the following errors:

A failure was encountered while launching the process serving application pool 'WAP'. The application pool has been disabled.

or

The identity of application pool 'WAP' is invalid, so the World Wide Web Publishing Service can not create a worker process to serve the application pool. Therefore, the application pool has been disabled.

then you may need to grant some permissions to the account you are using.

Here is a list of things to try

• Add user to IIS_WPG group
• Add user to local admin group and adding the "Act as part of the os" right.
• run aspnet_regiis -ga "domain\user" on the user account you are using
• Check password
• Grant the Log on as service role in local / group policy