This is nothing new and it has probably been written about hundreds (if not thousands) of times already, but since I’m only encountering the issue every few months or even more seldom, it always slips my mind and I end up wondering what’s wrong.

I’m talking about the fact that any custom identity being used for an application pool in Internet Information Services 6.0 must be a member of the IIS_WPG group which grants it all the necessary privileges. Unfortunately otherwise IIS reports only Service Unavailable when the site gets accessed without any additional information which makes it kind of difficult to determine the cause of the problem.

Hopefully this post will help reminding me of this fact when I need it the next time.