Teams Message: An unexpected error occurred. Tag: 7q6ca Code: -2147023838 at logon to Teams time

Hello @Борис Скринник

I would like to summarize the issue you are experiencing to ensure we are aligned:

• On a standalone (non-domain-joined) PC: You can sign in successfully to both the Teams web version and the desktop application.
• On a domain-joined PC: You can sign in via a web browser, but the desktop application fails with error: Tag: 7q6ca Code: -2147023838.
• Account Status: You use only one Microsoft account (originally created for Skype).

This error does not mean you have multiple accounts or that your credentials are incorrect. On domain-joined PCs, the Teams desktop app utilizes Windows sign-in information saved on the computer, which can sometimes conflict with personal Microsoft accounts. This explains why the web version works while the desktop app fails specifically on the domain-joined machine.

Before proceeding, please confirm if you have selected the "Personal account" option during sign-in. You may refer to this Microsoft article regarding your situation: Which account do you want to use?

Additionally, I suggest the following troubleshooting steps:

1/ Disconnect the Account from Windows Settings

• Go to Windows Settings > Accounts > Access work or school.
• If your email is listed, select it and click "Disconnect". (This only prevents automatic login conflicts and will not delete your account).
• Restart Teams and try signing in again.

2/ Clear the Teams Cache

• Close Teams completely (ensure it is quit from the taskbar).
• Press "Win + R", type %appdata%\Microsoft\Teams, and press Enter.
• Delete all files and folders in this directory.
• Restart Teams.

Clear the Teams client cache - Microsoft Teams | Microsoft Learn 

3/ Select the Correct Account Type

If prompted to choose between a "Work or school account" or "Personal account," always select Personal account, as your login originated from Skype.

If you still need my assistance, please come back with screenshots or any additional details so I can review it again and see if there’s anything more I can help you with.  

Have a nice day!  

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I have ONE account.

ONE.

I do not have any other account than i've created for Skype many years ago, and it works in 3/4 cases I already wrote above.

Thanks.