Is anyone else seeing this sign-in error when opening Office.com and selecting "View account"? The login page reports: "AADSTS900023: Specified tenant identifier '{{{tenantid}}}' is neither a valid DNS name, nor a valid external domain." It has been happening for users in both Europe and the United States, and appears to affect multiple organizations.
2 Answers
There doesn’t seem to be a confirmed workaround yet. If access is still unavailable, check Microsoft’s service health information when possible and open a support request so the incident is associated with your tenant. Since the error references a placeholder tenant value, retrying locally is unlikely to fix it.
This appears to be a Microsoft-side authentication problem rather than an issue with a particular tenant or user account. Several organizations and regions are reporting the same error, so there may not be a local workaround beyond waiting for the service to recover.
I’m seeing the same behavior for a client, and it has continued for more than an hour. Opening a support case with Microsoft seems to be the main option for now.