Office365 PowerShell command connect-msolservice reports "Unable to authenticate your credentials" [Solved]
We've been having issues with a customer today whereby the Office365 PowerShell command connect-msolservice reports the following Unable to authenticate your credentials. Make sure that your user name is in the format: <username>@<domain>. If this issue persists, contact Support. We've investigated this and confirmed the credentials are correct and that the user account can log into the Office 365 admin portal. Eventually we found that the domain user account we were executing the PowerShell command connect-msolservice as was the problem. Logging onto the computer as a different account (but using the same Office 365 credentials) worked. We didn't get to the bottom of why as the domain account was a root domain admin, however using a different account resolves the issue. If we get any more details we will post them here but at least there's a workaround for this very misleading error.