OWA unexpected error – HTTP redirect and Outlook Web Access

Shortening the adress from webaccess.customer.com/owa to webaccess.customer.com can lead to OWA unexpected errors.

The problem can be the HTTP redirect set in IIS.

Fix it by changing iistart.htm

HTTP redirect to avoid /owa in the URL

 
Many Exchange administrators make the online access to Outlook (OWA) easier for their users by configuring an HTTP redirect to /owa within the IIS.
The extension /owa behind the web address is not necessary anymore.
But the configuration can lead to certain errors.

The benefit

To use his or her Outlook account online, the user just has to type:
webaccess.customer.com instead of
webaccess.customer.com/owa

OWA unexpected error by using the IIS built in redirect

You can use the built in method of IIS by configuring the option HTTP redirect on the default-website.
It’s hard to recognize at first sight that the configuration is inherited to all the pages below.
This can lead to the OWA “unexpected error” when working with the calendar or on the contacts.

Change iistart.htm to HTTP redirect /owa instead

It is safer to set up the OWA HTTP redirect by changing the file iisstart.htm in the directory wwwroot.
It should be replaced with a file containing the redirect.
Here is an example how it could look like:

I hope it helps you fixing this OWA unexpected error as well. Feel free to comment if you have further suggestions.