I'm trying to add a VCSA 8 IA to an AD domain (Domain and Forest @ 2016) and I'm getting 'idm client exception error 31'.
There are no firewalls between VCSA and AD DC.

I tried it on the command line to see if I could get more input, got error 1f, this is the end of the logfile:

Any thoughts or help would be appreciated. Thanks.