SOLVED: Server 2012 – Remote Desktop Connection Broker server could not enumerate the targets for the provider named NULL from the database

If you see the following error on your Server 2012 RD install:

The Remote Desktop Connection Broker server could not enumerate the targets for the provider named NULL from the database.

Pooled virtual desktop collection name: NULL
Error: Logon to the database failed.

you likely have either an old domain or one that was upgraded from an old domain and you need to manually add your Remote Desktop server into the MEMBER OF tab of “Windows Authorization Access Group” via Active Directory Users and Computers.

For great detail see THIS KBase article.  I also found THIS Technet discussion useful.