500 Internal Server Error for Exchange 2007 Outlook Web Access

In an Exchange Server 2007 environment you may encounter the following error when users attempt to access Outlook Web Access.

500 – Internal server error.

There is a problem with the resource you are looking for, and it cannot be displayed.

The error occurs when user access OWA via the /exchange path but not the /owa. For example:

• https://mail.company.net/owa (gets no error)
• https://mail.company.net/exchange (gets the 500 internal error)

This can occur when the Exchange 2007 Mailbox server is missing the Web-ISAPI-Ext feature. You can check this by logging on to the server and running this command:

C:\>servermanagercmd -q | findstr "Web-ISAPI-Ext"
            [ ] ISAPI Extensions  [Web-ISAPI-Ext]

If there is no check mark next to the feature then it will need to be installed by running the following command:

C:\>servermanagercmd -i web-isapi-ext
..

Start Installation...

[Installation] Succeeded: .
[Installation] Succeeded: [Web Server (IIS)] Application Development.
[Installation] Succeeded: [Web Server (IIS)] ISAPI Extensions.

Success: Installation succeeded.

When you check the status of the feature it will now show as installed.

C:\>servermanagercmd -q | findstr "Web-ISAPI-Ext"
            [X] ISAPI Extensions  [Web-ISAPI-Ext]

That should resolve the “500 internal error” when accessing OWA via the /exchange path.