Microsoft Exchange OWA and the dreaded HTTP 500 error

Here is an issue I see just infrequently enough to forget it.  When accessing OWA (Outlook Web Access), the following interaction takes place.

1. The user accesses OWA via a web browser and receives the logon page.
2. The user enters his/her credentials and presses the Sign in button.
3. The user is presented with a 500 Internal Server Error screen.  The address indicated is https://myexchangeserver.mydomain.com/owa/auth.owa.  The title bar typically indicates HTTP 500 Internal Server Error.

The most common cause for the above behavior is the “Microsoft Exchange Forms-Based Authentication service” is not started.  Sometimes this service does not automatically start at boot.  Simply starting the service will correct the issue.

In case the above is not causing the issue, there is another easy step to correct the issue.  Reset the OWA virtual directory.  Below are the PowerShell commands.

• Get-OwaVirtualDirectory ‘SERVER\owa (Default Web Site)’ | fl
• Remove-OwaVirtualDirectory ‘SERVER\owa (Default Web Site)’
• New-OwaVirtualDirectory -WebSiteName ‘Default Web Site’

In all of the above commands, replace SERVER with the actual server name.
The first command is to get all settings for OWA.  This can be useful if it is later determined there were custom settings that need to be restored.  The second command removes the existing virtual directory.  The last command creates a new OWA virtual directory will all default settings.

If after doing all of the above, and the issue remains, it is time to start going through the IIS (Internet Information Server) logs and the event viewer to determine the cause of the problem.

If you have another scenario where OWA is generating a 500 Internal Server Error I want to hear about in the comments section.