MRS Proxy Error ‘The connection to the server could not be completed’

KB ID 0001358


When attempting a cross forest mailbox migration, When specifying the ‘Remote MRS Proxy Server address’ you get the following error;

MRS Error-The connection to the Server Could Not Be Completed


the connection to the server ‘server-fqdn‘ could not be completed


Note: For Office 365 Environments see below.

This tripped me up for quite a while, (it kept saying access denied). I’d tested this previously and everything was working. Note: If you have never had it working, ensure that the name you are using is resolvable in DNS and it’s the name on the certificate of the MRS Proxy server, (or at least a subject alternative name) See this link for how to set it up properly.

Assuming, (like me) everything is OK and the MRS proxy service is running etc, then I found the root cause of my problem by running;

Get-MigrationEndpoint | fl

MRS Error Get-MigrationEndpoint

I saw the problem straight away, it was using ‘cached credentials for an admin user who had changed their password, now all I had to do was work out how to replace the credentials!

Within the the Exchange admin center > Recipients > Migration > {Ellipsis} > ‘Migration Endpoints’.

Exchange Migraiton Endpoint Settings


Migration Endpoint Credentials

Enter the new (correct credentials)  > Save > Save.

Change Migraiton Endpoint Settings

Now retry your ‘batch’ migration.

Office 365 Migration Endpoint Error

If you get the same error when attempting to setup a Migration Endpoint in Office 365;

MRS Office 365 Endpoint Error

Then simply skip setting up the endpoint, and perform a batch migration, the system will then connect to the MRS proxy service and work.

Related Articles, References, Credits, or External Links


Author: PeteLong

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  1. THANK YOU!!!! I am so happy I found this before getting a little crazy. I was having thoughts of redoing the hybrid configuration – so glad you wrote this. Thank you!

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  2. Thanks! for me the administrator associated with the endpoint did it, i run an excchange 2010 hybrid.

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  3. THANK YOU PeteLong, IT WORKS !

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  4. Thank you so much! I had TWO cases with MS and neither of them checked this. You have save me so much trouble!
    Thank you so much!

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  5. Thanks so much for posting this! Exactly what I was looking for. Saved me a call with MS.

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  6. Thank you for this article. It saved my time.

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  7. Thanks a lot for this post, saved me a lot of time.

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  8. I am glad I did not spend too much time to find your posting. It worked. Appreciate your sharing!

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  9. Found this super helpful when an admin password was changed mid day and caused Hybrid Office 365 migration to come to a halt – SUPER THANKS!!

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    • Nice one, thanks Shawn – glad to know I’m helping someone!

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  10. Hi, great article.
    This service account what role or what rights does this service account need in order to do the migration ?

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    • I usually ensure I’m in the Exchange Organisational management Group

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  11. I also needed to enable Basic Auth on the EWS virtual directory before my on-premises MRS proxy could be used by O365…

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  12. Thanks! This saved me a lot of time!

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  13. Same error Exchange 2016, unfortunately didn’t resolve my issue. Creds were mine, re-entered, same error.

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  14. THANK YOU! I fixed the error… a few hours ago I changed a passwd from a Domain Admin, and that was the cause! I made a new user account for this migration setting only!

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    • what is the permissions that you assign to the user

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      • I just use a user with Organisational-Management, group membership.

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  15. Thank you… the steps works

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  16. Thanks, had the same problem!

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  17. This simply resolve the “Remote MRS Proxy Server” error displaying “The connection to the Server “” could not be completed” that was coming up during the hybrid migration exercise to Office 365.

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  18. Thanks, it worked perfect

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  19. Great find!. Thank you very much. It helped fix the issue.

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