Whenever I plug headphones into the Librem 14 laptop 3.5mm jack running Qubes OS v.4.2.1 the laptop spontaneously hard reboots. I am running the Embedded Controller v1.13 and latest Pureboot. Position of cam/mic hardware switch makes no difference.
Is anyone else experiencing this problem?
I have the same problem. Some weeks ago I got a reply from support that this is a known issue with EC 1.13. As a workaround one can downgrade to EC 1.12, but I care more about fast brightness adjustment than about wired headphones 
Thanks for confirming. I’ll keep an eye out for the next EC firmware release. Until then will make sure my headphones are plugged in at boot or use my USB headphone adapter.
Ah, cool, I did not know that plugging them in before booting already is fine. So thanks to you too!