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I'm running Kubuntu 20.04. 3 out of 4 times when I shutdown or reboot, it hangs at:

 Reached target Reboot.
 systemd-shutdown[1]: Waiting for process: crond

I've spent a fair bit of time googling, but have unable to figure out why it's doing this. It makes frequent reboots agonizingly slow. I did find one thread describing the same issue on the Ubuntu forums, but they failed to post their solution (just that they solved it).

Any help or info would be greatly appreciated.

  • Does the same happen when you use dcron instead of crond? Have you always been having this problem or is it something that arouse after taking some action? – David Kariuki Jun 5 at 22:36
  • This is a relatively fresh Kubuntu install, and I'm relatively new to Linux. I was basically working on getting everything installed, and at some point, this radomly started happening. It's unclear exactly when, particularly because it only occurs intermittently. Not sure what I would need to change to 'use dcron instead of crond'? – Metal450 Jun 5 at 23:49
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+50

Cron can hang if one of its jobs is hanging (for example if you have a misconfigured log rotation, etc.).

To find the culprit run pstree before you reboot to see if any processes are active/hanging:

pstree -ap $(pidof cron)

You can also look what cron jobs are defined in

/etc/crontab  
/etc/cron.d/  
/etc/cron.daily/  
/etc/cron.hourly/  
/etc/cron.monthly/  
/etc/cron.weekly/

as well as crontab -l (for each user).

If this does not help you solve your problem you can use this as a workaround:

  • edit /etc/systemd/system.conf

  • set DefaultTimeoutStopSec in the Manager section

    [Manager]
    DefaultTimeoutStopSec=5s
    
  • run systemctl daemon-reload

This will tell systemd to only wait for 5 seconds for the crond process to exit.

| improve this answer | |
  • Even after setting timeout to 5 seconds it's still taking around 3 minutes to shutdown and the same message pops up (waiting for process crond) – Mateen Kiani Sep 25 at 7:59
  • Since this is not your question you cannot update it with the output of journalctl -b -1 -r ...? check if there are any messages related to crond. It should say "Shutting down." before "Reached target Reboot." (the log is reversed with -r) – laktak Sep 25 at 8:15

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