SupportMultipleDomain is not supported here

I’m working onsite this week for a customer who recently replaced their ADFS servers after the originals disappeared into the mists of Azure. Attempting to convert a new MSOL domain from Managed to Federated resulted in the following error:

PS C:\> Convert-MsolDomainToFederated -DomainName <domain2_fqdn> -SupportMultipleDomain
Convert-MsolDomainToFederated : The switch parameter SupportMultipleDomain is not supported here.
At line:1 char:30
+ Convert-MsolDomainToFederated <<<<  -DomainName <domain2_fqdn> -SupportMultipleDomain
+ CategoryInfo          : InvalidOperation: (:) [Convert-MsolDomainToFederated], FederationException
+ FullyQualifiedErrorId : MultipleDomainSwitchNotSupported,Microsoft.Online.Identity.Federation.Powershell.ConvertDomainToFederated

Resolution as follows:

Open ‘AD FS 2.0 Management’
Expand ‘Trust Relationships’
Expand ‘Relaying Party Trusts’
Right-click the trust and delete

Open ‘Microsoft Online Services Module for Windows PowerShell’
Update the existing Federated domain(s):

PS C:\> Update-MsolFederatedDomain -DomainName <domain1_fqdn> -SupportMultipleDomain
Successfully updated '<domain1_fqdn>' domain.

Convert the remaining Managed domain(s):

PS C:\> Convert-MsolDomainToFederated -DomainName <domain2_fqdn> -SupportMultipleDomain
Successfully updated '<domain2_fqdn>' domain.

I’d also seen this issue a few months back with another customer under different circumstances. They’d try to add additional domains to a subscription but their first domain wasn’t converted with the SupportMultipleDomain parameter. The resolution was exactly the same – delete the relaying party trust and then update/convert the domains.

You should also verify that the MsolFederationProperty values match on-premise and online:

Get-MsolFederationProperty -DomainName <domain1_fqdn>

If the on-premise and online values don’t match then correct as follows:

Update-MsolFederatedDomain -DomainName <domain1_fqdn>