Today as was trying to fix an issue regarding with ADFS and Office 365.
The Issue:
A very simple error, when you try to add the second domain it fails and in this case it was because the first federated domain was not setup using –SupportMultipleDomain
The solution:
After some digging and searching I found this post:
https://exitcodezero.wordpress.com/2013/03/05/supportmultipledomain-is-not-supported-here/
The issue was not exactly the same but close enough, a bit further down in the post it seems that he had the same issue as a while back.
Delete the object in the ADFS console
Open up the ADFS mmc snap-in
and delete it
Switch from Managed to Federated
Open the elevated PowerShell prompt with the Msol CMDLets, connect and authenticate and run this command to fix it:
Convert-MsolDomainToFederated -SupportMultipleDomain -DomainName viamonstra.com
From this point on, you can now switch from Managed to Federated on all the other domains as well
Last thing you do is to run:
Get-MsolDomain to verify:
/mike
Share this:
Categories: ADFS, Office 365
The Deployment Bunny 
5 years on, this helped me. The error message is so entirely non-descriptive.
Thank you.