Just to add to that

the VirtualDirectories is a very simple script which gets it's values throug:

Get-OabVirtualDirectory -server "servername"

the servername is obtained by asking the machine name through the powershell SolidCP Server is on (so always make sure it's ran on a CAS Server)

Hmm.. It doesn't really make sense :/

The code seems to be working as it should, and when checking the verbose log I also get the correct OAB virtual dir:

[12/11/2016 4:37:21 PM] INFO: Exchange   OAB Virtual Dir: <exchange server hostname>OAB (Default Web Site)

But for some reason it must break on it's way through the script since SolidCP tries to run this command:

[12/11/2016 4:37:21 PM] INFO: Exchange New-OfflineAddressBook -Name 'bjerggaard.me Offline Address Book' -AddressLists 'bjerggaard.me Address List' -IsDefault $False -GlobalWebDistributionEnabled $False -VirtualDirectories System.String[] -DomainController '<dc fqdn>'

That is the proper outcome yeah.

Any chance you have any restrictions , filters or caches enabled on IIS that messes up the soap call (anything non-standard iis) ? (as it hops back and forth from enterprise to solidcp server for this script)

There shouldn't be anything non-standard setup, the only thing i've done in the IIS manager is changing the stuff as written in the guide for SolidCP and Exchange 2016.

hmm..

that where about all the ideas i had to check at the moment.

it's a bit late now, but i will try and think about some other things to check and get back to you tomorrow.

If i am still out of ideas, i will be happy to do a remote session with you (do note the rule for that is the fee that applies with 1:1 support, all profits go back into SolidCP tho)