Why won't Buster Lite boot to anything other than emergency mode on wired Pi Zero when a file system check is done?

Question

I'm running a wired (no onboard bluetooth or wifi) Pi Zero with Buster Lite with latest update/upgrade. When I touch /forcefsck, or put an equivalent statement in /boot/cmdline.txt, it ALWAYS fails the same way. It boots ok if I don't do a file system check on boot. I'm using a brand new Samsung 64 GB micro SD card and the only thing I've done is apt-get update then apt-get upgrade. This is the second identical micro SD card in a row with which I'm having this problem with the identical OS, which I mention because some people have speculated that the speed of the card is important.

The error message I get during boot is:

(green) [OK] Started Helper to synchronize bootup for ifdown
(red) [TIME] Timed out waiting for device /dev/ttyAMA0
(yellow) [DEPEND] Dependency failed for Serial Getty on /dev/ttyAMA0
(red) [TIME] Timed out waiting for drive /dev/disk/by-partuuid/xxxxx
(yellow) [DEPEND] Dependency failed for /boot
(yellow) [DEPEND] Dependency failed for local file system
(yellow) [DEPEND] Dependency failed for file system check on /dev/disk/by-partuuid/xxxxx

It then goes into emergency mode, where the cursor often unfortunately returns to the start of the line so my login overwrites the text that is already there.

On the first card I tested, I disabled wifi and bluetooth in /boot/config.txt, and it helped a little but not enough.

How do I fix this ?

Answer 1

In my case the problem was caused by "File System Check on Root Device" task that timed-out. The error output was actually the same as yours so it was not very clear to me.

What solved this issue for me was adding:

DefaultTimeoutStartSec=300s

into /etc/systemd/system.conf (increasing time-out from the default 90s).

Explanation: The issue started to happen after I installed f2fs-tools package. I use F2FS for my root file system and the fsck command runs for approximately 2 minutes on my 16 GB SD card (more than the default Systemd time-out). Before I installed the package, the fsck command simply skipped checking the file system and finished immediately.