Why am I having trouble signing in to Microsoft Teams?

This article offers a few FAQs about modern authentication, including what it is and what to do if you run into any problems.

If you’re an IT admin and want more detailed information about how to resolve a sign-on problem, see Modern authentication and Microsoft Teams.

What is modern authentication?

Microsoft Teams has implemented a better way of signing in—we call it modern authentication. (If you’ve ever heard the term “single sign-on ” or “SSO”, that’s what we’re talking about here.) The benefit of modern authentication is that it makes it possible for you to sign in to Microsoft Teams without re-entering your email and password every time you want to start a new session. It’s a more secure and reliable way to sign in to Microsoft Teams.

Modern authentication is a process that allows you to sign in to an app securely. Since modern authentication includes SSO, it’s also part of the process that lets Microsoft Teams know that you've already entered your credentials (like your work email and password) elsewhere, and you shouldn't be required to enter them again to launch the app.

Signing in with modern authentication will vary depending on a couple things, like if you're working in Windows or on a Mac. It will also vary depending on whether your company has enabled single-factor authorization or multi-factor authorization (multi-factor authentication usually involves verifying your credentials via your phone, by providing a unique code or entering a PIN number or presenting your thumbprint). Either way, once you complete the sign in process using modern authentication, you won’t be required to provide your credentials again—from that point on, Microsoft Teams will automatically sign in to your account once you launch the app from the same machine.

Why can't I sign in?

Modern authentication is great, but there’s a possibility that an organization will run into the occasional problem.

Every organization that uses Microsoft Teams already has modern authentication—the app has been delivered with modern authentication hard-wired into it, and it should be able to recognize your credentials as linked to your Office 365 account. If you're not able to complete the sign in process, there might be something wrong with your domain or your company's Office 365 account. Your IT admin or sysadmin will be your point person in terms of resolving the issue, so get in touch with them to get more information and next steps.

For more information on access to Microsoft Teams, see How do I get access to Microsoft Teams.

What does the status code at the bottom of my error message mean?

If you received an error message while attempting to sign in to Microsoft Teams, look in the bottom left corner of the window—you should see a status code. This information is going to be very important to your IT admin in diagnosing what went wrong with your sign-in process, so make a note of your status code and communicate it to them. If you’re curious about what your status code means or want to try basic troubleshoot procedures, you can look up the status code in the table below.

Note: In many cases, only your IT admin or sysadmin will be able to resolve the issue for you. So after trying the basic troubleshooting suggestions in this table, contact them with the status code in this table.

Known issues

Code

Description

Troubleshooting action

0xCAA20003

You ran into an authorization problem.

Make sure your date and time are set up correctly. Whether your date and time are accurate will affect your ability to connect to secure sites (https).

0xCAA82EE2

The request has timed out.

Ensure that you are connected to the Internet. Then work with your IT admin to ensure that other apps or a firewall configuration aren't preventing access.

0xCAA82EE7

The server name could not be resolved.

Ensure that you are connected to the Internet. Then work with your IT admin to ensure that other apps or a firewall configuration aren't preventing access.

0xCAA20004

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

Contact your IT admin so they can confirm that your organization is complying with Azure Active Directory (AAD) configuration policies.

0xCAA90018

You’re not using the right credentials.

The Windows credentials you signed in with are different than your Office 365 credentials. Try to sign in again with the correct email/ password combination. If you continue to receive this status code contact your IT admin.

none

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

Re-insert your smart card. Also, your smart card certificate might be corrupt, in which case, contact your IT admin.

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