Just upgraded using the module admin and during the upgrade core 12.0.9 was installed and all my extensions stopped being reachable. I received a DECLINED message. Looking through the logs during a CLI> monitor sessions it appears that 'sub-record-check GOSUB command was not found in extensions_external.conf. I did a GREP of the /etc/asterisk folder and found [sub-record-check] in extensions_external.conf.bak and put it back into extensions_external.conf manually.
I could then dial extensions.
I understand this file is written by FreePBX and it may break in the future now. But I wanted to post this that the upgrade to this caused the system to not function.