Additional features, settings, or issues not covered by specific Microsoft Teams categories
Hi Johnwildes,
According to the error, please try the following 2 methods to give it a shot:
1. Go to your control panel>manager credential> clear the credential (cache). Then re-start your Team client.
2. Go to the System Tray and right-click on the Teams icon
Select Log Out
The app will go through the motions of logging off and restart, then ask for your credentials. Enter your O365 credentials.
Here I say Office 365 credentials as Microsoft Teams can be signed into with a Microsoft account credentials.
Regards,
Alan