Hey,
I’m trying to dual boot Endeavour OS with Windows 11, I only have 1 drive, and created a 200 GB partition for Endeavour. I’m installing it using Endeavour OS Mercury Neo with a USB stick, which I loaded using Rufus.
When installing it, first it made some progress but at 12% it just got stuck with the “Process running in background…” messages for a bit before crashing with the “Failed to run pacman” error.
I did run the mirror updaters before starting the installer, and my C drive is mounted correctly.
I then saw this post Installation "Failed to run pacman" error, and tried the fix there, it then went to 32% before getting stuck on “Process is running in the background…” for 45 minutes
Issue is around internet connection or mirrors used, log does not show much about only what you wrote already,
i do also not see this in the log only hanging on fetching packages.
What i can recommend to try is to manually rank mirrors before starting installer. Automatic ranking inside installer is not always giving the best results in cases.
And i do not think the post you linked too is related to your issue.