Printer freaks out suddenly during normal print

Your error is:

Timeout with MCU 'mcu' (eventtime=6493.810291)
Transition to shutdown state: Lost communication with MCU 'mcu'

See Timeout with MCU / Lost communication with MCU
Since this is an intermittent issue, it is unfortunately difficult to diagnose, but so far it has always been traced back to some sort of hardware instability.