CODES LIBRARY
Error code hub pages and scenario fixes
Some Microsoft error codes (0x80070005, CAA50021) recycle across multiple contexts. The hub page tells you what the code means; the scenario page tells you how to fix it where you saw it.
Code hubs
Each hub explains what the code is, then routes you to a context-specific fix.
Microsoft 365 Error CAA50021
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
OneDrive Error 0x8004de40
OneDrive error 0x8004de40 means the client can't connect to the cloud. Here's exactly what the code means, the real causes, and the fix order that works.
onedrive error 0x8004de40
OneDrive Error 0x8004de90
OneDrive error 0x8004de90 means your account isn't fully set up — usually a license or provisioning issue, not a network problem. Here's the fix.
onedrive error 0x8004de90
Teams Error 80090016
Teams error 80090016 says the TPM has malfunctioned. It almost never has. Here's the fix that works first, and why most guides start with the wrong one.
teams error 80090016