I've been running Linux Mint now for ~10 years after earlier forays into Gentoo, Slackware & Arch. Back when I was a teenager and I didn't have the cash to purchase new hardware and needed to squeeze every inch of performance out of my machines, distributions which gave me fine-grained control of what was running in the kernel & user space not only gave me this last bit of performance, but also taught me a lot about running Linux & GNU in general.
Since moving over to Linux Mint, things have usually "just worked" without the need for me to actively manage my OS. Unfortunately, computers are computers and sometimes things break. I don't have to reboot often, though I do like to keep my machine up-to-date. After keeping my machine up for a month or two, I noticed that suddenly I was experiencing catastrophic failure--the network was working, but Network Manager was not. I was unable to perform many tasks on the machine, therefore, I rebooted.
The machine appeared to reboot fine, albeit taking ~5 minutes longer than normal, though once I entered into X is when I noticed that lightdm was not coming up--I would see a pointer on a black screen before X cycled into a loop, exiting to a blinking cursor and then back to the black screen with pointer.
Quickly dropping into my terminal & killing lightdm, I began reviewing the lightdm logs to see exactly where the problem lay. I saw several lines like so:
WARNING: Failed to get list of logind seats: GDBus.Error:org.freedesktop.DBus.Error.TimedOut: Failed to activate service 'org.freedesktop.login1': timed out (service_start_timeout=25000ms)
WARNING: Error getting user list from org.freedesktop.Accounts: GDBus.Error:org.freedesktop.DBus.Error.TimedOut: Failed to activate service 'org.freedesktop.Accounts': timed out (service_start_timeout=25000ms)
Thinking possibly that a package broke my system, I proceeded to perform an apt update / apt upgrade, though while running apt I also was seeing the following suspicious error:
Reading package lists... Done