Fix Microsoft Teams Error CAA50021: Number Of Retry Attempts Exceeds Expectations (2025)

Updated: 12/1/2025

You open Microsoft Teams for a meeting, click Sign in, and instead of your chats you see an error like "Error code CAA50021" or a message that the number of retry attempts exceeds expectations. Teams refuses to log you in, keeps spinning, and may even work in the browser while the desktop app is broken.[web:7][web:19]

This error is usually not a full account ban, it is almost always a mix of cached tokens, old credentials or device registration problems on Windows. The fixes below focus on clearing that broken data so Teams can request a clean authentication token again.[web:10][web:13]

Method 1: Basic Restart And Network Check

Before jumping into deep fixes, rule out the simple causes that often trigger CAA50021, such as a glitchy app session or a flaky Wi Fi connection.[web:7]

Step 1: Quit Teams completely

In Windows, click the Teams icon in the system tray, choose Quit, then open Task Manager and make sure there are no Teams.exe processes still running, if you see any, right click and select End task so the app really closes.

Step 2: Restart your PC and router

Restart your computer to clear temporary auth data in memory, then power cycle your router by turning it off for 30 seconds and back on, this helps if the error was triggered by brief connectivity drops while Teams was refreshing tokens.[web:7]

Step 3: Test sign in on the web

Open a browser and go to https, , //teams, microsoft, com, try signing in with the same account, if the web app works fine but the desktop app still shows CAA50021, that is a strong sign that the problem is with local cache or device registration, not your Microsoft 365 account itself.[web:13]

Method 2: Clear Microsoft Teams Cache On Windows

Corrupted cache files in the Teams app data folder are one of the most common reasons for CAA50021, clearing them forces the app to rebuild its local configuration and token cache.[web:7][web:10]

Step 1: Close Teams and open the Run dialog

Quit Teams from the system tray, then press Windows key + R to open the Run box, you will use it to jump straight into the hidden AppData folders.

Step 2: Delete the Teams cache folders

In the Run box, paste the following path and press Enter, this opens the core Teams cache location for your user profile.

Inside that folder, delete the contents of these subfolders if they exist, Cache, databases, GPUCache, IndexedDB, Local Storage and tmp, do not worry, Teams will recreate them the next time you sign in.[web:7][web:10]

Step 3: Restart Teams and sign in again

Start Microsoft Teams from the Start menu and sign in with your work or school account, the first launch may take a little longer while it rebuilds cache, if CAA50021 was caused by corrupted local data, you should now reach your chat list normally.

Method 3: Remove Old Teams Credentials And Re join Azure AD

If clearing cache is not enough, the stored Windows credentials and Azure AD device registration might be out of sync, removing those entries forces Windows to request fresh tokens the next time you log into Teams.[web:10][web:19]

Step 1: Remove Teams credentials from Credential Manager

Open the Control Panel, switch view to Large icons, then click Credential Manager, go to Windows Credentials and look for any entries that mention MicrosoftOffice, Teams, Microsoft, Office, 365 or your organization domain, expand each related credential and click Remove.[web:10]

Step 2: Re register the device with Azure AD if needed

Some users fix CAA50021 by leaving and re joining Azure AD so their device registration resets, on a corporate machine only do this if your IT allows it, open an elevated Command Prompt by searching for cmd, right clicking, and choosing Run as administrator, then run the following command to unjoin the device.

Restart the PC, then sign back into your work account under Settings > Accounts > Access work or school, Windows will re register the device and issue new tokens.[web:19]

Step 3: Launch Teams and verify

Open Teams again and try to sign in, if the underlying token problem has been cleared, the CAA50021 message should disappear and you should be able to join meetings and access chats as normal.