Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
This worked for me:
Go to "Work and school accounts" in Windows settings, disconnect the mail account there and open Outlook again. Now it asks for the password and everything works again.
Orriginal post https://www.reddit.com/r/Outlook/comments/12qzo46/outlook_error_1200_when_trying_to_set_up_and/?rdt=53518