Which “fresh firmware”? What norns version are you running?
add_group was added in norns 200323
You might need to run SYSTEM>UPDATE?
EDIT: Although, probably unrelated - I get the following error after updating to the most recent norns version. This does not cause an init error, but just throws the error in maiden while launching.
# script run
>> reading PMAP /home/we/dust/data/cheat_codes/cheat_codes.pmap
m.read: /home/we/dust/data/cheat_codes/cheat_codes.pmap not read.
lua: /home/we/dust/code/cheat_codes/cheat_codes.lua:2005: attempt to index a nil value (global 'step_seq')
stack traceback:
/home/we/dust/code/cheat_codes/cheat_codes.lua:2005: in global 'grid_redraw'
/home/we/dust/code/cheat_codes/cheat_codes.lua:869: in field 'event'
/home/we/norns/lua/core/metro.lua:169: in function </home/we/norns/lua/core/metro.lua:166>
But… does not error on subsequent loads. 