Outlook Web Access fails with "440 Login Timeout"

Today I faced an interesting problem. A customer told me that their Exchange 2010, which is currently part of a Exchange cross-forest migration project, has an issue with Outlook Web Access and the Exchange Control Panel. Both web sites fail with a white screen and a single message:

440 Login Timeout

I checked some basics, like certificate, configuration of the virtual directories and I found nothing suspicious. Most hints on the internet pointed towards problems with the IUSR_servername user, which is not used with IIS 7 and later. But authentication configuration and filesystem permissions were okay. Also the IIS end event logs were pretty unhelpful.

More interesting was the change date of the web.config! This file is part of the OWA web app and it’s typically stored under C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\Owa.

Long story short: I found this entry in the file and removed it.

<add name=”kerbauth” />

Looks like someone wanted to setup Kerberos auth for OWA, or did not reverse a change.