The Citrix Desktop Service failed to obtain a list of delivery controllers with which to register.

Funny little problem.

So I installed VDA 7.13 on a brand new Server 2016. Did the usual to create a catalog etc. But the VM doesn’t register with the Delivery Controller. Application event logs are filled with messages like these:

The Citrix Desktop Service failed to obtain a list of delivery controllers with which to register. 
 
Please ensure that the Active Directory configuration for the farm is correct, that this machine is in the appropriate Active Directory domain and that one or more delivery controllers have been fully initialized. 
 
Refer to Citrix Knowledge Base article CTX117248 for further information. 
 
Error details: 
Exception 'Value cannot be null.
Parameter name: values' of type 'System.ArgumentNullException'

Please ensure that the Active Directory configuration for the farm is correct, that this machine is in the appropriate Active Directory domain and that one or more delivery controllers have been fully initialized.

Refer to Citrix Knowledge Base article CTX117248 for further information.

Error details:

Exception 'Value cannot be null.

Parameter name: values' of type 'System.ArgumentNullException'

I am not looking to AD etc. for the list of Delivery Controllers, so why this error? Open up regedit and HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\VirtualDesktopAgent\ListOfDDCs has the correct names too. So what gives?!

Turns out when I put in the Delivery Controllers name here I had set them as “DC1.fqdn. DC2.fqdn.“. I could ping either of these and connect to the ports etc from the VM, but just on a hunch I removed the “.” in the “fqdn.” and tada! it began working. :)

Moral of the story: Citrix Desktop Service expects Delivery Controllers to be of format “DC1.fqdn DC2.fqdn“. If it sees a dot it ignores the ListOfDDCs key and looks towards AD. It doesn’t tell you that it’s ignoring the registry key, so you are stuck wondering why it’s looking towards AD. :)