HTTP Error 503. "The service is unavailable."

Question

One of my Web Applications shows error:

HTTP Error 503. The service is unavailable

I checked in IIS Application pool and started the respective services but the error still persist

How can I solve this?

Answer 1

The Issue is fixed now,

The Error is because of the service account credentials

Thanks pals for your inputs

Answer 2

Please check if there are some errors in the Event Viewer. It might give you a clue. In my situation I had to low memory. And the logs in Event Viewer told me about it.