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louiscilo's avatar
louiscilo
Copper Contributor
Aug 22, 2023
Solved

Exchange 2013 hybrid upgrade to Exchange 2019 Hybrid, outlook keep prompting m365 login.

Hi,

 

I have Exchange 2013 with Hybrid Modern Auth enabled. I am planning to migrate to Exchange 2019 hybrid. Outlook is 2019.

 

Everything works fine in EXCH13 hybrid environment. However when installed the first EXCH19 server in environment, internal users' outlook start to prompt m365 login box. No matter cancel or input credential, the box will prompt every 1 - 2 minutes. But once I switch off the EXCH19 server, everything works fine again without problems. External users might have this issue too, but haven't got any complain yet.

 

All mailboxes are still in EXCH13 now. No mailboxes on Cloud. HCW should be fine as EXCH13 hybrid are running for long time already...

 

I have no idea what happening. No error logs, email flow seems ok. Please kindly assist!

2013
2019
Exchange Server
hybrid
outlook
  • louiscilo's avatar
    louiscilo
    Sep 07, 2023
    Updated:
    It is fixed by running Set-AuthServer -RefreshAuthMetadata.
    Should be the cache issue, but still no idea why the metadata won't update by servers automatically.

2 Replies

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  • louiscilo's avatar
    louiscilo
    Copper Contributor
    Sep 07, 2023
    Updated:
    It is fixed by running Set-AuthServer -RefreshAuthMetadata.
    Should be the cache issue, but still no idea why the metadata won't update by servers automatically.
  • LeonPavesic's avatar
    LeonPavesic
    Silver Contributor
    Aug 22, 2023

    Hi louiscilo,

    The continuous M365 login prompts you're encountering can be resolved by following these steps:

    1. Check Autodiscover Configuration: Ensure that your Autodiscover DNS records are set up correctly and pointing to the right location. You can do this by verifying the Autodiscover URL settings in both Exchange 2013 and Exchange 2019 servers.

      Autodiscover service in Exchange Server | Microsoft Learn

    2. Certificate Configuration: Double-check your SSL certificate on the Exchange 2019 server. Make sure it covers all the required domains, including Autodiscover and Exchange services. If there's an issue with the certificate, it can lead to login prompts.

      [SOLVED] Exchange 2019 certificate verification (spiceworks.com)
      Import or install a certificate on an Exchange server | Microsoft Learn

    3. Review OAuth Configuration: Verify that Hybrid Modern Authentication (OAuth) is properly configured on both your Exchange 2013 and Exchange 2019 servers. This secure authentication method is important for seamless communication between on-premises and online services.

      Configure OAuth authentication between Exchange and Exchange Online | Microsoft Learn

    4. Authentication Methods and Protocols: Confirm that the authentication settings (like NTLM, Basic, and OAuth) match between your Exchange 2013 and Exchange 2019 servers. 

    5. Check URLs and SCP Records: Make sure the URLs you've configured in both versions of Exchange are accurate and consistent. Also, check the Service Connection Point (SCP) records in Active Directory to ensure they're pointing to the right Autodiscover service.

      Please click Mark as Best Response & Like if my post helped you to solve your issue.
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      Kindest regards,


      Leon Pavesic

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