Recently, a customer with a federated active directory setup got an error from the MS Online Services Team saying that they did not register a synchronization for at least 24 hours. The synchronization has been working fine until now but then suddenly stopped.
We noticed the following errors in the event viewer.
The management agent "TargetWebService" completed run profile "Delta Confirming Import" with a delta import or delta synchronization step type. The rules configuration has changed since the last full import or full synchronization.
To ensure the updated rules are applied to all objects, a run with step type of full import and full synchronization should be completed.
An unknown error occurred with the Microsoft Online Services Sign-in Assistant. Contact Technical Support. GetAuthState() failed with -2147186688 state. HResult:0. Contact Technical Support. (0x80048831)
If you notice similar errors, try to login to https://portal.microsoftonline.com with the AD Sync user credentials, most likely the password has expired and needs to be changed. Once you’ve changed the password run the Active Directory Sync Config tool and update the credentials.