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.

500 Internal Server Error for Exchange 2007 Outlook Web Access

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

  • (gets no error)
  • (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.

About the Author

Paul Cunningham

Paul is a former Microsoft MVP for Office Apps and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul no longer writes for


  1. Horace

    Thanks Paul, I got this error with a CCR cluster running on Server 2008R2. The thing is I was using the flat URL and redirecting to /exchange. I think ISA was redirecting to /exchange instead of /owa. I guess that is what happens when a customer runs outdated versions!

    1. Nasser

      How to solve the problem

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