Please read this:
Please also don’t forget to come back to your question after your issue has been solved and click the 3 dots below the answer to mark a solution like this below the answer that helped you most:
so that the next person that has the exact same problem you just had will benefit from your post as well as your question will now be in the “solved” status.
(No not this one! One of the excellent answers above)
P.S. My machine has been running stably (with a minor problem left and right) since:
head --lines=1 /var/log/pacman.log
[2019-12-07T17:04:33+0100]