M365
Sign-in & work-school account
3 articles on sign-in & work-school account.
Microsoft 365 Error CAA50021: What It Means and How to Fix It (2026 Updated Guide)
CAA50021 is a Microsoft 365 work/school account sign-in error. Here's what it actually means, the one fix that resolves most cases, and when to stop and call IT.
caa50021
Microsoft 365 MFA Prompt Loop: Three Patterns, Three Fixes
Microsoft 365 MFA prompt loops aren't one problem — they're three. Here's how to identify which pattern you're seeing, and the fix for each. End-user and admin paths.
microsoft 365 mfa prompt loop
Microsoft 365 'Something Went Wrong' Sign-In Error: How to Read the Bracket Code and Fix It
The 'Something went wrong' Office sign-in error has a code in brackets. Here's how to read [1001], [4vt9f], [657rx], and the rest — and the fix order that actually works.
microsoft 365 something went wrong sign in