Forum Discussion

Rob Axelrod's avatar
Rob Axelrod
Copper Contributor
Jun 29, 2020
Solved

After a hybrid migration to Exchange Online Outlook clients not switching over.

Migrating users from Exchange 2010 to O365. Clients are using Outlook 2016 MSI install. After a successful migration, Outlook goes into the "disconnected" state and doesn't prompt for O365 credential...
office 365
outlook for windows
  • ChristianBergstrom's avatar
    ChristianBergstrom
    Jun 29, 2020

    Rob Axelrod Hello, not in my comfort zone here but I've heard of an almost identical issue before where they disabled MFA (temporarily) to get it to work.

     

    If that's not the case maybe this is applicable

    https://support.microsoft.com/en-us/help/3073002/after-migration-to-office-365-outlook-doesn-t-connect-or-web-services

ChristianBergstrom's avatar
ChristianBergstrom
Silver Contributor
Jun 30, 2020

Rob Axelrod Hey Rod! Glad to hear that the solution worked for you! But I can't say I know what's going on as the "456 authentication error" should indicate that MFA is enabled for your account while modern authentication is not enabled in EXO. Perhaps open a MS ticket as you said all those settings are OK.

 

PeterRising Any idea?

Rob Axelrod's avatar
Rob Axelrod
Copper Contributor
Jun 30, 2020
I have a ticket open to look at the conditional access settings. Modern Auth is definately enabled since every other scenario works just fine except for the specific act of transitioning the Outlook client from on prem to the cloud post hybrid finalization. I think the answer is going to be tweaking my conditional access config so that the "Other Clients" setting isn't checked in the policy that requires multi factor.
  • Carlos67's avatar
    Carlos67
    Copper Contributor
    Mar 27, 2021

    Rob Axelrod I'm also interested in knowing Ms's response to your ticket. I am doing a migration and I have encountered the same problem. Thanks.

  • ChristianBergstrom's avatar
    ChristianBergstrom
    Silver Contributor
    Jun 30, 2020

    Rob Axelrod Great! Would you mind sharing the response when you get it? Thanks!

    • PeterRising's avatar
      PeterRising
      MVP
      Jun 30, 2020

      Rob Axelrod I have no idea which particular CA policy setting might be at fault I'm afraid.  Definitely one for MS ticket.  As ChristianBergstrom says, I'd be interested to hear the outcome as well.