Turns out that Microsoft Dynamics GP 2015 does not support Microsoft SQL 2016 CTP 3.3. It appears to be something with the ODBC connections that it doesn’t like. The message tells you to upgrade to version 11 even though that is the version packaged within SQL 2016.
So being the genius I am I installed a named instance of SQL 2014 after uninstalling the native client first that came with SQL 2016. Long story short is I’ve wrecked my test lab and I’ll be spending this evening rebuilding it. Fun times indeed!