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rupam2021 avatar image
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Exchange 2010 to Exchange 2016 mailbox move - OWA/Outlook not working

We have installed Exchange 2016 servers on our existing Exchange 2010 environment.
There's a load balancer (host: owa.domain.com) that routes traffic to Ex2010 CAS servers.
Now, we just did a cutover so that owa.domain.com now points to Exchange 2016 servers.

After the cutover, we found the following:
1. Ex2010 mailbox working fine on owa/outlook
2. We migrated one mailbox from Ex2010 to Ex2016 database, after migration we cannot access the mailbox using https://owa.domain.com / outlook.
3. But, after the mailbox migration, the mailbox can be accessed if we access it using the Ex2016 server name (https://Ex2016/owa)

To summarize, the mailboxes hosted on Ex2016 server/db are only accessible if we access it via https://Ex2016/owa url , but its not working if we use the load balanced host - https://owa.domain.com


Can anyone please help to fix the issue so that we can also the Ex2016 mailboxes using owa.domain.com url ?

Thanks in advance.

office-exchange-server-connectivity
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KaelYao-MSFT avatar image
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KaelYao-MSFT answered KaelYao-MSFT converted comment to answer

Hi @rupam2021

When you access the URL owa.domain.com/owa, did you see the legacy Exchange 2010 OWA interface?
And what is the detailed error message when you fail to login?

Please try adding ?ExchClientVer=15 to the URL (owa.domain.com/owa?ExchClientVer=15) and see if you are directed to the Exchange 2016 OWA interface.


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Hi @rupam2021

I am writing here to confirm with you how thing going now?
Did the issue get resolved?

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rupam2021 avatar image
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rupam2021 answered

Hi @KaelYao-MSFT ,

Thanks for your response.
We found that the Load Balancer +WAF was blocking the client connections. This is because at the LB/WAF, only the urls/cookies/headers related to Exchange 2010 were allowed. Since Ex2016 has additional urls/cookies/headers on the requests (made by client), these requests were being blocked at LB.
I asked MS support to provide a list of URLs/Cookie names/ headers that are used in Ex2016 owa/ecp communication, but they said no such list is available. Currently we are manually whitelisting each new URLs/cookie/headers in the LB to make it work.

If you have any other suggestions, i would be happy to test it.

Thanks.

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Hi,

Thanks for the update.
Glad to hear you have found the cause of the issue.

I have converted your reply to an answer, please feel free to mark it as the answer to the question.
It may be helpful to other community members who come up with the same problem.

Thanks for your sharing!

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