How do I resolve Azure AD Connect upgrade error 'E_MMS_SCHEMA_NO_CLASSES'?

Nathan Gracie-Raitt 1 Reputation point
2020-06-08T05:01:27.567+00:00

Environment is a small AD environment with a working-until-3-weeks-ago installation of Azure AD Connect.

In my troubleshooting to restore password synch functionality, I noticed that there was a version upgrade, so I thought I'd try that, rule out that as a source of my problems.

Except that, after running the MSI setup, and launching the wizard to complete the upgrade, it throws the error I mention in the subject line.

Environment: Database is well under 8GB with < 100 users in this domain. Server 2019 on both the app server running AADConnect and the AD DS servers. Current patches installed on both. No recent firewall changes that would get in the way of comms from the AAD server and the internet (and therefore: MIcrosoft infrastructure where AADConnect will need to communicate in order to do it's job).

A copy of the logfiles for my environment are here.

Microsoft Entra ID
Microsoft Entra ID
A Microsoft Entra identity service that provides identity management and access control capabilities. Replaces Azure Active Directory.
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  1. Marilee Turscak-MSFT 33,706 Reputation points Microsoft Employee
    2020-06-09T00:34:08.907+00:00

    If you have MFA enabled, you may want to make sure that MFA is disabled in portal.azure.com and portal.office.com > active users. That might be able to fix the sync for the error that you mentioned in the main post.

    If that doesn't work or if you already do not have MFA enforced, you may need to run IdFix to check for duplicates, missing attributes, and rule violations.

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