Overview:
When your Microsoft 365 password is changed, you must also change this manually in the customer portal. Follow this step-by-step article if your password needs to be updated in the Synchronizer.
This will solve the issue if you keep seeing the Credentials Expired error message in the customer portal when using Microsoft 365.
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Wait until you see the "Timer" and click the Edit Credentials button.
Click the Sign in with Microsoft button and fill in your Microsoft 365 credentials.
Click the Save button at the bottom of the page