What you’re seeing
- Teams, Outlook or another Office app shows error code CAA2000B during sign-in.
- A message says something went wrong or that your organization requires this device to be registered.
- The same user signs in without trouble on another computer or in a web browser.
- The error appeared after the computer was reimaged, renamed or moved between domains.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The computer's Microsoft Entra device registration is broken or missing, so device-based access rules block the sign-in.
- A Conditional Access policy requires a compliant or hybrid-joined device, and this machine doesn't meet the condition.
- The Trusted Platform Module that protects the device's sign-in keys is malfunctioning or was recently cleared.
- The local token broker cache holds stale credentials from a previous account or tenant.
- A proxy or traffic inspection tool interferes with the connection to Microsoft's sign-in service.
Why it matters
CAA2000B blocks access to Teams, Outlook and the other Office apps on the affected device, cutting the user off from chat, meetings and email on their main computer. Because it is tied to device trust, it often appears after hardware swaps or rebuilds, exactly when a user is trying to get back to work. Bypassing the device requirement to get them in quickly weakens the security controls your organization put in place for a reason.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Why does the error only happen on one computer?
CAA2000B is usually tied to the device's registration or security chip rather than the user's account, which is why the same person can sign in elsewhere.
Will the computer need to be wiped and reinstalled?
Rarely. In most cases the device's registration or token state can be repaired over a remote session without rebuilding Windows.