Hi @Ketil Larsen
Welcome to our forum!
What is your account? Outlook.com or Microsoft 365 or something else?
Does the issue occur recently on Outlook Desktop Client? Do you have any specific operation before the issue occurred?
As i know: Error Tag: 657rx is likely caused by your organization's settings/policies (e.g. conditional access policy). Please Go to Settings>Accounts>Access Work or School>Then removed any account that was in there by hitting Disconnect>After that launch Outlook or any Office app and sign in to see if the error persists.
More information: how to fix "Something went wrong. [657rx]" - Microsoft Q&A
Hope it helps!
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