Hi, I have the same issue with mcomix = 3.1.0-1
Issue look like appear after python3 upgrade 3.13.3-1 -> 3.13.5-1.
Matohara San's pach (thanks !!!) works also for me.
Edit your /usr/lib/python3/dist-packages/mcomix/__main__.py
and change:
mp.set_start_method('spawn')
to:
try:
mp.set_start_method('spawn')
except RuntimeError:
pass
Be careful for tabs, because Python is tab sensitive.
Best regards,
Olivier

