Newly created synced users cannot sign in resulting in AADSTS80018 (was: Cloud Sync Question - PHS Support)

Question

Hi

I'm facing the very same issue as described by another community member where user synced from originally Azure AD connect cloud sync are unable to sign in resulting int the otherwise (so far) not documented error code AADSTS80018.[1]

Cloud-only users can sign in and change passwords, but synchronized users originating from a Server 2022 AD cannot so the issue seems specific to users originating from AD.

While this is still in a test environment, urgency is lower, however based on the feed I have switched to the older AAD connect version and forced a new password hash sync without any change. Provisioning logs also look good as suggested by a MS employee on the previous thread.

The interesting part is that changing from cloud sync ot the legacy AAD connect didn't change anything since neither previously present, nor users created in the on-prem AD after switching back to legacy AAD connect remain affected.

Note: If you feel that this is a duplication of the preceding thread: I originally wanted to reach out to the Microsoft employee who had offered help to the original person, but Microsoft processes require that such contact can only be established by the original author and anyone else has to open a separate Q&A thread.

[1]: [1]: https://learn.microsoft.com/en-us/answers/questions/1257590/cloud-sync-question-phs-support