Bug#1114860: systemd: Confusing error message about missing "/etc/machine-id" upon setup

[Luca Boccassi]

Control: tags -1 wontfix
Control: close -1

On Wed, 10 Sep 2025 22:38:50 +0200 Hilmar Preusse <hille42 at web.de>
wrote:
> Package: systemd
> Version: 258~rc4-1
> Severity: minor
> 
> Dear Maintainer,
> 
> recently I noticed that setting up systemd failed to setup in one of
my
> chroots. The error message was:
> 
> <snip>
> root at rasppi3:~# apt build-dep texlive-bin
> Summary:
>   Upgrading: 0, Installing: 0, Removing: 0, Not Upgrading: 0
>   4 not fully installed or removed.
>   Space needed: 0 B / 58.3 GB available
> 
> Continue? [Y/n] y
> Error: Can not write log (Is /dev/pts mounted?) - posix_openpt (19:
No such device)
> Setting up systemd (258~rc4-1) ...
> Cannot open '/etc/machine-id' in neither writable nor read-only mode:
Function not implemented
> dpkg: error processing package systemd (--configure):
>  installed systemd package post-installation script subprocess
returned error exit status 1
> Errors were encountered while processing:
>  systemd
> Error: Sub-process /usr/libexec/apt-eatmydata/dpkg returned an error
code (1)
> Error: Failed to process build dependencies
> <snip>
> 
> The root cause turned out to be a not mounted /proc filesystem, the
setup
> worked fine after it was mounted. However I found that error message
quite
> confusing: the file /etc/machine-id is there and is readable.

It's accurate, but not helpful, as the file can't be read as file
descriptors can't be used without procfs. This is not a supported
setup, sadly procfs is a hard runtime requirement.