Exchange 2010 – Experiencing an OWA HTTP 500 Error?

I came across this error at a client site this morning.  You are presented with the login screen. You log in to the OWA site with the required username and password.  You are then presented with a “HTTP 500” error.

The first thing that comes across your mind is the Domain Controller is down.  You check, nope it is still online.  Then you start looking at the service…

If you have tried to stop and start the IIS service and reboot the server and still cannot fix the error, I have a solution for you.

So the issues is typically caused by the “Microsoft Exchange Forms-Based Authentication” service being stopped. Starting the service immediately fixes the issue.

I have still not found a good reason why.  I am sure Exchange 2013 has fixed this bug.