Microsoft Teams Troubleshooting

Teams sign-in blank or not working? Start here.

The sign-in window opens white or nothing loads at all. Before you spend an hour guessing, run the two-second browser test below. It tells you exactly which half of the problem you are dealing with.

Do this first

Open teams.microsoft.com in your browser and try signing in.

Browser works, app does not

Desktop app issue. Focus on WebView2 and the manual fix steps below.

Browser also fails

Account or network issue. Start with the diagnostic tools below, then jump to steps 4 and 5.

Teams sign-in diagnostic

Runs in the Microsoft 365 admin center. Enter the affected user's email address and it checks their account configuration for known sign-in blockers.

Requires Microsoft 365 admin account. Not available in Government or 21Vianet tenants.

Run the diagnostic

Remote Connectivity Analyzer

Tests whether the user's account can actually reach Microsoft's authentication endpoints. Catches network and connectivity blocks that the admin center test does not cover.

Not available in GCC or GCC High Government environments.

Run connectivity test

Most likely fix for a blank sign-in window

Install the WebView2 Runtime

Teams uses a component called WebView2 to render the sign-in window. If it is missing or outdated on your PC, the window loads blank. Installing it fixes the problem for most people.

Download WebView2 Runtime

Choose the Evergreen Standalone Installer → install → restart your PC → try Teams again.

Update the Teams desktop app

Teams updates automatically, but occasionally falls behind. Check for a pending update before anything else.
Teams → top-right menu (three dots) → Check for updates

Check your system clock

A wrong time or time zone silently breaks the authentication tokens Teams relies on. Make sure both are set automatically.
Settings → Time & language → Date & time → turn on "Set time automatically" and "Set time zone automatically"

Clear cached credentials

Windows stores login tokens for Teams and Office. When those go stale, they block a fresh sign-in. Delete them so Windows fetches new ones.
Credential Manager → Windows Credentials → remove any entries containing "Teams" or "MicrosoftOffice"

Reset or fully reinstall the Teams app

A corrupted installation can cause a blank sign-in window even with WebView2 in place. Try the Reset option first. If that does not work, uninstall fully, delete the leftover Teams folder, then reinstall clean.
Settings → Apps → Microsoft Teams → Advanced options → Reset
For a full reinstall: uninstall Teams, then delete the %appdata%\Microsoft\Teams folder, then reinstall from teams.microsoft.com/downloads. Right-click the installer and choose Run as administrator.

Pause your VPN and antivirus, then test on a mobile hotspot

Security software and VPN tunnels can intercept the sign-in flow without showing a clear error. Temporarily disable them, switch your PC to your phone's mobile data, and try again. If it works there, the issue is your local network or a security tool blocking Microsoft's authentication endpoints.

0xCAA82EE7
0xCAA82EE2

No internet or network connectivity issue

Teams cannot reach Microsoft's servers. Confirm the device has internet access. Then use Microsoft's Network Assessment Tool to verify the required IP addresses and ports are reachable. If you are on a corporate network, your firewall may be blocking the endpoints Teams needs. Check the Microsoft 365 URLs and IP address ranges list.

0xCAA20004

Conditional Access is blocking the sign-in

A Conditional Access policy in your tenant is preventing this device or user from signing in. This is an admin-level fix. The policy may require a compliant device, an approved app, or MFA that the device cannot satisfy. Check your Conditional Access policies for Teams in Entra ID.

0xCAA70004
0xCAA70007

Office 2016 connection issue (also affects other Office apps)

If this error appears in Teams and you are also having sign-in issues in other Office apps, it is likely an Office 2016 build conflict. See Microsoft's guidance on connection issues after updating to Office 2016 build 16.0.7967.

Error code not listed here? Microsoft maintains a full reference at Why am I having trouble signing in to Microsoft Teams? If the sign-in loop only happens in the Teams web client, see the separate guide on Teams stuck in a login loop.

Need a hand setting Teams up for your business? Whether it's rolling Teams out for your whole company or setting up the Teams Phone System, MStack360 can handle it for you.

Teams Phone System setup

None of these worked?

At this point it is usually a Conditional Access policy, a licensing gap, or an Entra ID configuration that needs an admin to resolve.

These are not things you can fix from your own machine. We can check your tenant, identify the exact cause, and fix it on the first call.

Book a free call

Microsoft reference: learn.microsoft.com — Resolve sign-in errors in Teams