Fixes / Teams · Checked September 30, 2026

Teams error code CAA7000a: what it means and how to fix it

Short answer

Teams error code CAA7000a (0xCAA7000A) is a sign-in failure in the Teams desktop app. The app couldn't finish talking to Microsoft's sign-in servers, usually because of a dropped or blocked network connection or a broken local cache. The fastest fix is to disconnect and reconnect Wi-Fi, quit Teams fully and sign in again. If that fails, reset the Teams app in Windows Settings.

What this message means

CAA7000a belongs to the CAA family of Teams sign-in status codes. These codes come from the Microsoft sign-in component that the desktop app uses to get your work or school token. Microsoft lists its close relatives (CAA70004, CAA70007, CAA82EE2) as connection problems: the server couldn't be reached, the connection was interrupted, or the request timed out. CAA7000a works the same way. The app gave up before sign-in finished. Your password and account are almost always fine. The clearest sign is that Teams on the web (teams.microsoft.com) signs in normally on the same computer while the desktop app doesn't. That puts the problem on the device: its network path, its cached data, or its stored credentials.

Common causes

Cause	How to tell
Unstable, switching or captive network connection	The error shows up right after waking the laptop, changing Wi-Fi networks, or joining hotel or guest Wi-Fi. Other websites may load slowly, and retrying a minute later sometimes works.
VPN, proxy, firewall or antivirus blocking Microsoft sign-in addresses	The error happens only while the VPN is on, only on the office network, or started after a new security product was installed. Teams on the web may also hang at the sign-in page on that network.
Corrupt Teams cache or app data	The web version works fine, other Microsoft 365 apps sign in normally, and the desktop app shows the error every time, even on a good connection.
Stale saved credentials or a broken work account link in Windows	Outlook, OneDrive or Word also ask you to sign in repeatedly or show similar CAA codes, or the problem started after a password change.
Wrong system date, time or time zone	The clock in the taskbar or menu bar is off by several minutes or more. Some secure websites may also show certificate warnings.
Outdated or damaged Teams install (including leftover classic Teams)	Teams hasn't updated in a while, you still have the old purple-icon classic Teams, or none of the other fixes change anything.

How to fix it

1. Reconnect to the network and retry

Quit Teams completely: right-click the Teams icon in the taskbar (or Dock on Mac) and select Quit.
Turn Wi-Fi off, wait 10 seconds, and turn it back on. If you can, try a wired connection or a phone hotspot instead.
If you use a VPN, disconnect it, or connect it if your company requires it for Microsoft 365.
Open https://teams.microsoft.com in a browser to confirm your account signs in on this network.
Start Teams again and sign in.

2. Check the date and time, then check for updates

On Windows 11, open Settings > Time & language > Date & time. Turn on Set time automatically and Set time zone automatically, then select Sync now.
On Windows 10, the same options are in Settings > Time & Language > Date & time.
On a Mac, open System Settings > General > Date & Time and turn on Set time and date automatically.
If Teams gets past sign-in, select Settings and more (...) next to your profile picture and choose Check for updates.

3. Reset new Teams or clear its cache

New Teams on Windows 10 and 11, and Mac. Classic Teams on Windows: clear %appdata%\Microsoft\Teams instead.

Quit Teams from the taskbar or Dock icon.
Windows (easiest): open Settings > Apps > Installed apps (on Windows 10, Apps > Apps & features), search for Microsoft Teams, select More options (...) > Advanced options, then select Reset. This removes your Teams personal settings.
Windows (manual): press Windows key + R, enter %userprofile%\appdata\local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams and delete everything in that folder.
Mac: open Terminal and run rm -rf ~/Library/Group\ Containers/UBF8T346G9.com.microsoft.teams, then rm -rf ~/Library/Containers/com.microsoft.teams2
Start Teams again. The first launch takes longer while the cache rebuilds.

4. Remove saved Microsoft credentials and re-add your work account

Windows 10 and 11

Quit Teams, Outlook and the other Office apps.
Open Control Panel > User Accounts > Credential Manager > Windows Credentials.
Under Generic Credentials, expand entries that start with MicrosoftOffice16 or msteams, and select Remove for each.
Open Settings > Accounts > Access work or school. If your work account shows an error, select it, choose Disconnect, then add it again with Connect. Skip this on a company-managed PC unless IT approves, because disconnecting can unenroll the device.
Restart the computer and sign in to Teams.

5. Rule out firewall, antivirus and proxy blocking

Temporarily pause third-party antivirus or firewall software (not Microsoft Defender), then retry sign-in. Turn it back on right after.
If sign-in then works, add an exception for Teams (ms-teams.exe for new Teams) in that security product.
Open Command Prompt as administrator and run ipconfig /flushdns to clear stale DNS entries.
On a work network, ask IT to confirm that the Microsoft 365 sign-in endpoints (login.microsoftonline.com and related addresses) aren't blocked or intercepted by the proxy.

6. Reinstall Teams cleanly

Uninstall Microsoft Teams from Settings > Apps > Installed apps (Windows) or drag it from Applications to the Trash (Mac). Also remove any leftover classic Teams.
On Windows, press Windows key + R, open %appdata%\Microsoft, and delete the Teams folder if it exists.
Download the current Teams installer from microsoft.com/microsoft-teams and install it.
Restart the computer and sign in.

Next time, skip the search

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Still not fixed?

Try signing in to the desktop app from a different Windows user profile or a different computer. If it works there, the problem is local to your original profile. If it also fails on another network and another device, your organization's setup is the likely cause. Contact your IT admin with the exact code shown at the lower left of the Teams sign-in window. Admins can run the Teams Sign-in diagnostic in the Microsoft 365 admin center or the Teams Sign in test at testconnectivity.microsoft.com. They can also check Entra ID sign-in logs for Conditional Access or network blocks. If your account is personal rather than work or school, contact Microsoft Support and use Teams on the web in the meantime.

Questions people ask

Why does Teams work in the browser but show caa7000a in the desktop app?

The web version uses your browser's sign-in session and network path. The desktop app uses its own sign-in component, cache and saved Windows credentials. When the browser works, the fault is almost always the app's cache, stored credentials, or a security tool filtering the desktop app's traffic.

Does error caa7000a mean my account is locked or my password is wrong?

No. A wrong password produces a different code (0xCAA90018) or a clear password message. CAA7000a means sign-in didn't finish, usually because of a connection problem.

Does running Teams in compatibility mode or as administrator fix caa7000a?

Some users of classic Teams reported that it did. New Teams installs as a Store-style (MSIX) app with no compatibility tab, so reset the app or clear its cache instead.

Will clearing the Teams cache delete my chats or files?

No. Chats, files and meetings are stored in Microsoft 365 and download again after you sign in. You only lose local settings such as theme and notification preferences.

Can I use Teams while I fix this?

Yes. Go to https://teams.microsoft.com in Edge or Chrome and sign in with the same account. Chats, meetings and calls all work there.

Sources

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