My favorite was when the behavior of a USB drive in /etc/fstab
went from "hmm it's not plugged in at boot, I'll let the user know" to "not plugged in? Abort! Abort! We can't boot!"
This change over previous init behavior was especially fun on headless machines...
This happened to me when Debian switched from SysV to systemd. I am not the only person who experienced this (e.g., https://bbs.archlinux.org/viewtopic.php?id=147478 ).
This is not to say the systemd behavior is wrong, but it essentially changed the behavior of
fstab
. Whether this is Debian's fault, Arch's fault (per the above link), systemd's fault, or my fault is a fair question. But this committed that most egregious of sins per our Lord and Savior Torvaldsit broke my userspace.