At attempt to verify a domain for Office 365 service in
Domain verification failed: MS Graph API server error: 'Domain verification failed with the following error: 'Domain takeover failed paramName: name, paramValue: example.com, objectType: Microsoft.Online.Workflows.DomainOperationNotAllowedException'.'.".
Actual error can be obtained if we try to verify the domain on the Microsoft Portal directly:
We have confirmed that you own example.com, but we cannot add it to this tenant at this time. The domain is already added to a different Office 365 tenant: anotherdomain.onmicrosoft.com.
Provide the information to end - customer. Contact Microsoft Technical support if necessary.