Hi Experts -
I am troubleshooting a strange issue, and can't seem to resolve it.
We are currently in the middle of an Exchange migration project from 2010 to 2013. Everything has been relatively smooth until now.
Our 2013 OWA server allows users to log in, both internally and externally without issue. If the user's mailbox is already migrated to Exchange 2013, they have no issue. If the user has a 2010 mailbox, they are able to log in, get redirected to the proper 2010 OWA server and put into their mailbox. However, as soon as they make any action at all, they are kicked back to the 2013 OWA login page. This issue is not happening to ALL 2010 users, but it is definitely happening to the majority of them. I can't seem to find anything in the logs that points to what is causing the issue.
Some answers to possible questions for clarity:
- This issue occurs whether a user is connecting to OWA internally, or externally.
- This issue occurs whether a user connects via https://webmail.domainname.com/owa
or directly to https://exchange2013serverhostname.domain.local/owa
- This issue does NOT occur if a 2010 mailbox user connects to https://exchange2010serverhostname.domain.local/owa
- This issue does not happen to 100% of 2010 mailbox users, but does happen to most of them.
- This issue does not happen if I create a brand new 2010 mailbox, and connect to OWA 2013, and get redirected to the 2010 version to get into their mailbox
- In the event that I migrated an affected user's mailbox to 2013, the issue goes away. However, we are not prepared to fully migrate everyone right now, so this isn't a viable option.
I'm thinking it might be an IIS issue, but on all Exchange OWA servers, the authentication settings are the same, and if a 2010 users logs into 2010 OWA directly, everything works fine. If a 2013 user logs into 2013 OWA directly, everything works fine. It's just when a 2010 user logs into the 2013 OWA login page, then gets redirected to their mailbox on 2010 (which is intended), when they click on ANY item at all within the page, they get kicked back to the 2013 OWA login page again.
Thanks in advance.