grblHAL Alarm 16

grblHALAlarmPosition isn't set yet: home first

The controller's power-on self test failed.

Position isn't set yet: home first. Nothing has been homed yet. (Hamrun's reading)
What to do
  1. Power the controller off and on.
  2. If it repeats, check the controller's own documentation or support: the board found a fault in itself.
Official grblHAL message: “Power on selftest (POS) failed.” source

Got a different message?

Paste it into the decoder. Hamrun's editor checks your G-code before you run it, so a toolpath that leaves the machine's travel or a missing feed rate is caught before the machine stops.

Official text copied from the grblHAL source on 2026-11-01. Steps and the position answer are Hamrun's reading unless marked “firmware says”. User reports are labelled CLAIMED.