For our better research, please provide more information about this case:
- What is the account type? (Exchange local accounts/Microsoft 365 accounts/others)
- Do other users in your organization have the same problem?
- Can other office applications (Word, Excel, OneNote) log in normally?
Depending on your description, please try the following possible solutions:
- Update your browser to the latest version and make sure you have a high-speed internet connection.
- For Teams to be able to sign in independently, try clearing your browser cache and then signing back in: https:\\teams.microsoft.com.
- Contact your administrator to verify sign-in issues, Run Test: Teams Sign-in.
- For Outlook, disable ad blockers or pop-up blockers, specifically: AdBlock and Ublock.
- Check that the operating system meets the requirements: Supported browsers for Outlook on the web and Outlook.com - Microsoft Support.
Hope this helps!
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