What are all the possible mistakes when signing up for Teams?

Here are the most common errors and their cause:

0xCAA20003:
A problem occurred during authorization.

Make sure the date and time are set up correctly. The correct date and time are critical for connections to secure websites ("https").

0xCAA82EE2
The request has expired.

Make sure you are connected to the Internet. Then contact your IT administrator to ensure that other apps or a firewall configuration are not preventing access.

0xCAA82EE7
The server name could not be resolved.

Make sure you are connected to the Internet. Then contact your IT administrator to ensure that other apps or a firewall configuration are not preventing access.

0xCAA20004
Your request needs to be approved by a resource owner or authorization server.

Ask your IT administrator to verify that your organization complies with Azure Active Directory (AAD) configuration policies.

0xCAA90018
You are not using the correct credentials.

The Windows credentials you used to log in do not match your Microsoft 365 credentials. Try signing in again with the correct email address and password combination. If you still see the status code, contact your IT administrator.

You need to re-enter your PIN using a smart card.

Insert the smart card again. Your smart card certificate may also be damaged. In this case, contact your IT administrator.