How to Fix Can’t Sign into Microsoft Teams Error Code CAA2000B on Windows 10?

Microsoft Teams is a reliable product offered by Microsoft like its other services but recently Teams login error such as error CAA2000B is being reported by many users on numerous online support forums. The problem arises when a user tries to log in to his/her account. The error is extremely frustrating as it prevents users from using MS Teams which ultimately stops their education/business work. This creates an unfavorable experience for end-users as it directly affects their work. The error notification is as follows:

Error Notification

What Causes Can’t Sign into Microsoft Teams Error Code CAA2000B?

We have listed down some of the causes of this problem after reviewing the user’s feedback and technical authorities in detail. This problem may arise due to any of the following reasons:

  • Outdated MS Teams: Old versions of MS Teams may not be compatible with updated Windows 10 thus, creating unfavorable circumstances for MS Teams application to run properly, ultimately causing this error.
  • Corrupted Cache: Everyone knows how much harm corrupt files could do to your installed applications as well as to your computer. Corrupted cache data blocks authentication certificates which ultimately cause this error.
  • Bad Internet Connection: Another key reason for the MS Teams application to show this error can be your internet. A shared or weak internet connection may hinder the login process.
  • Incorrect Date & Time: Microsoft applications work relative to the date & time. Privacy & security patches also get updated relative to date & time. Therefore, if the date & time is incorrect on your PC then you are most likely to get the error under consideration. Certain websites may even refuse connection from your internet.
  • Azure Active Directory (AAD): The error may also arise when your organization is not complying with the Azure Active Directory (AAD) configuration policies. These policies are adopted to enhance both security and privacy.
  • Windows Credentials Clash: Most users are not aware of the fact that Microsoft’s database is different for both Windows Account and Office 365 Account. Users may be using the wrong credentials i.e. Windows credentials for O365 applications, ultimately causing this error.

Note: Before attempting any solution, quit the Microsoft Teams application from Task Manager to ensure you won’t lose any data. Furthermore, please sign into MS Teams using Web Browser to see if you can sign in there. In case you can, this error is strictly because of your Microsoft Teams desktop application.

Solution 1: Reset Internet Settings

As discussed in causes, bad internet connection or faulty internet settings may cause this problem. Users were able to resolve this issue after they had reset Network Settings. Follow the steps given below:

  1. Click Start, search Internet Options, and open it. This will open a window that contains internet related settings i.e. General, Security, Privacy, etc.
    Opening Internet Options
  2. Switch to the Advanced tab and click Reset. Windows will now initialize resetting all internet options, discarding all the settings that were made to them.
    Resetting Internet Settings
  3. Now launch Microsoft Teams and try to log in. This should fix your problem.

Solution 2: Clear Microsoft Teams Cache

As discussed in causes, corrupted cache data blocks authentication certificates which ultimately cause the error under consideration. Many users have reported that resetting/clearing MS Teams cache data helped them in resolving this problem. In this solution, methods for both Windows 10 and macOS have been provided. Kindly follow the steps followed by your operating system to fix this error.

For Windows 10 users:

  1. Right-click on the taskbar and select Task Manager from the list.
    Opening Task Manager
  2. Look for Microsoft Teams in the Processes section, right-click and select End Task. This will terminate all the background ongoing processes related to MS Teams.
    Closing MS Teams
  3. Click Start, search File Explorer and open it.
    Opening File Explorer
  4. Copy-paste the following location address in the address bar and press Enter. This will take you to a hidden folder named cache that contains cache files for MS Teams.
    %appdata%\Microsoft\teams\Cache
    Opening MS Teams Cache Directory
  5. Select all files by pressing Ctrl + A keys together on your keyboard and permanently delete all files in the folder by pressing Shift + Del keys together on your keyboard. Select Yes to confirm the deletion process.
    Deleting MS Teams Cache Files
  6. Now repeat the steps from 3 to 6 one by one for the following location addresses:
    %appdata%\Microsoft\teams\application cache\cache
    %appdata%\Microsoft\teams\blob_storage
    %appdata%\Microsoft\teams\databases.
    %appdata%\Microsoft\teams\GPUcache
    %appdata%\Microsoft\teams\IndexedDB
    %appdata%\Microsoft\teams\Local Storage
    %appdata%\Microsoft\teams\tmp
  7. Once you have deleted all files, try running Microsoft Teams and then logging in. This should fix your problem. In case it does not then proceed with the final solution.

For macOS users:

  1. Quit Microsoft Teams and copy-paste the following location address in spotlight search and press return. This will take you to a hidden folder named cache that contains cache files for MS Teams.
    ~/Library/Application Support/Microsoft/Teams/Cache
  2. Select all files by pressing command + A keys together on your keyboard and permanently delete all files in the folder by pressing option + command + delete keys together on your keyboard.
  3. Now repeat the steps from 3 to 6 one by one for the following location addresses:
    ~/Library/Application Support/Microsoft/Teams/Application Cache/Cache
    ~/Library/Application Support/Microsoft/Teams/blob_storage
    ~/Library/Application Support/Microsoft/Teams/databases
    ~/Library/Application Support/Microsoft/Teams/GPUCache
    ~/Library/Application Support/Microsoft/Teams/IndexedDB
    ~/Library/Application Support/Microsoft/Teams/Local Storage
    ~/Library/Application Support/Microsoft/Teams/tmp
  4. Select the Finder application, click Utilities on the Go menu, and then double-click Keychain Access.
  5. Find Microsoft Teams Identities Cache and delete it.
  6. Once done, try running Microsoft Teams and then logging in. This should fix your problem. In case it does not then proceed with the final solution.

Solution 3: Clean Uninstall & Reinstall MS Teams

If clearing the Microsoft Teams cache didn’t fix your problem then there is a strong possibility that some of the Microsoft Teams system files are corrupted. The easy fix would be to completely uninstall MS Teams and reinstall the latest fresh copy. This proved to be a helpful solution for many users online. Follow the steps given below to do so:

  1. Close MS Teams by right-clicking the MS Teams icon in the taskbar and select Quit. This will end all the background ongoing processes related to MS Teams.
  2. Right-click on Start and select Control Panel to open it.
    Opening Control Panel
  3. Select Uninstall a program under the Programs section. This will take you to the list of all installed programs on your PC.
    Opening Installed Programs List
  4. Select Microsoft Teams from the list of installed programs and click Uninstall. This will start uninstalling MS Teams. The procedure may take time so wait until it gets finished.
    Uninstalling Microsoft Teams
  5. Press Windows + R keys on your keyboard to open Run dialog box.  Type %appdata% and click OK. This will take you to a hidden folder named AppData where user data is stored for different applications installed on your PC.
    Opening AppData Folder
  6. Open Microsoft folder, right-click on Teams folder and select Delete.
    Deleting MS Teams Folder
  7. Close all windows and again press Windows + R keys on your keyboard to start Run. Type %Programdata% and click OK. This will take you to a hidden folder named ProgramData where program-related settings or data are stored.
    Opening ProgramData Folder
  8. Repeat step 6. Now you have finally uninstalled Microsoft Teams completely from your computer.
  9. Download a fresh updated copy of Microsoft Teams desktop setup from the Official Microsoft Teams Download Webpage and then install it. This should finally fix your problem.

Kevin Arrows


Kevin is a dynamic and self-motivated information technology professional, with a Thorough knowledge of all facets pertaining to network infrastructure design, implementation and administration. Superior record of delivering simultaneous large-scale mission critical projects on time and under budget.

Expert Tip

How to Fix Can’t Sign into Microsoft Teams Error Code CAA2000B on Windows 10?

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