[RD] [Credential Format] Credentials are not valid. Verify the username and password are correct and try to reconnect.
I entered the correct username and password, but Ti kept prompting me that my credentials were wrong. I could enter the management interface of Center. I could not enter the remote desktop in the management interface.
Karl Wester-Ebbinghaus (@tweet_alqamar) commented
Jeff sometimes it does make a difference whether you enter domain\username machinename\username or in case of a domain joined device using the UPN
If one sets up SSO this >usually< works without issues except with RDP.
Please recheck domain joined devices with or without SSO (delegated ...) for WAC. and make sure that UPN will be accepted.
domainname\username is pretty oldschool for me as O365 user / promoter:)
You must enter your account in the DOMAIN\USERNAME format (or MACHINENAME\USERNAME if not domain joined.)