Distro Can't upgrade to 16 from 15 with upgrade module

Trying to upgrade a distro 15 system to 16 using the PBX Upgrade module. The system passes all the checks, but at step 2 of the upgrade I just get an error page where the upgrade log should populate. If I hover the mouse over it, it says the pbx refused to connect.

nothing shows in /var/log/pbx