Welcome to our forum!
Please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. For our better research, please provide more information about this case:
What did you do when you get this error?
What is your email account type (Microsoft/Gmail/Other)?
Do you have the same problem logging into your email account using a browser?
Can you provide specific error messages or screenshots? Please make sure to overwrite your personal privacy information.