O365 iApp - Error: The Metadata Exchange URL in the domain registration isn't valid. URL:

just found the following devcentral article:

 

https://https://devcentral.f5.com/s/feed/0D51T00006i7fmESAQ

 

When doing some testing at https://portal.office.com I will get exactly the same error message:

 

AADSTS50000 there was an error issuing a token.

 

But what does it mean in detail?

 

Thanks Thrillseeker