How to Fix Microsoft Teams sign-in error caa20003
Error message
We're sorry — we've run into an issue. Status code: caa20003.
If you're seeing "Microsoft Teams sign-in error caa20003", you're not alone. Here's what it means, why it happens, and the steps to resolve it.
What this error means
The Teams desktop client couldn't complete the Web Account Manager (WAM) sign-in flow with Entra ID. Authentication is broken at the local account/token cache layer.
Why this happens
Stale or corrupted account entry in Windows, broken WAM token broker, conflicting Office sign-in, or a Conditional Access policy denying the call from the desktop endpoint.
Step-by-step fix
Sign out fully: Teams → click your avatar → Sign out, then quit Teams from the system tray.
Open Settings → Accounts → Email & accounts (and Access work or school). Remove any work/school account that looks orphaned, then re-add it.
Clear the Teams cache for the new client.
commandRemove-Item -Recurse -Force "$env:LOCALAPPDATA\Packages\MSTeams_8wekyb3d8bbwe\LocalCache"Reboot the machine (clears WAM in-memory state) and sign in again.
Affected products
Microsoft Teams
Still broken? Try these
- Try Teams web at teams.microsoft.com to confirm the account itself is healthy.
- Review Entra Sign-in logs for the user — a Conditional Access denial often surfaces here as caa20003.
- If the user just changed password/MFA, give the device a few minutes to refresh tokens.
Related errors
Frequently asked questions
What does "Microsoft Teams sign-in error caa20003" mean?
The Teams desktop client couldn't complete the Web Account Manager (WAM) sign-in flow with Entra ID. Authentication is broken at the local account/token cache layer.
What causes "Microsoft Teams sign-in error caa20003"?
Stale or corrupted account entry in Windows, broken WAM token broker, conflicting Office sign-in, or a Conditional Access policy denying the call from the desktop endpoint.
How do I fix "Microsoft Teams sign-in error caa20003"?
1. Sign out fully: Teams → click your avatar → Sign out, then quit Teams from the system tray. 2. Open Settings → Accounts → Email & accounts (and Access work or school). Remove any work/school account that looks orphaned, then re-add it. 3. Clear the Teams cache for the new client. 4. Reboot the machine (clears WAM in-memory state) and sign in again. Always test changes in a non-production environment first.
Browse more errors in Microsoft Teams: Fix Microsoft Teams errors. Desktop app loading issues, Teams Rooms audio/video drops, federation, and meeting access problems. Or paste your own error into the error decoder tool to find a match. You can also go back to the homepage to browse common errors by topic.