PBX with Ast 1.8 upgraded to FPBX 12 ok but can't move config to new Ast 11 box successfully

I’ve been messing around with this for over a week and need to get to the bottom of it. I have a new box built from the FPBX distro 6.12.65 with Asterisk 11. I upgraded my old 1.8 box from FPBX 2.10->2.11->12 which seems to be successful. Did a full backup, and restored to the new box. At first I think it’s working ok, but I keep getting crashes - starting and stopping amportal gives random php code errors - more than the missing licenses, etc - like functions not found, etc. Now I was changing an email address for a fax recipient in the GUI and when trying to update config (red button), I got similar php errors and a refusal to update. I just dropped back to my old box which seems stable, theoretically the only difference is Asterisk 1.8 not 11. Is there something flaky about moving a FPBX 12 config that I am missing? I did full backup and added voicemail and sounds. I only moved a few files from /etc/asterisk, namely voicemail.conf and extensions_custom.conf. I am throwing up my hands and sticking with the old box unless there is some procedure I am missing. Can anybody suggest anything to try?