Ubuntu – Suspend suddenly stopped working

1. Note down all the cron jobs for all users including root, for example:

To list the root's crontab

sudo crontab -l

To list your crontab

crontab -l

2. Delete the crontab complete for all users using the following

To delete the root's crontab

sudo crontab -r

To delete your crontab

crontab -r

3. Restart the system

4. Place your jobs back into the cron (Preferably the root's cron) either by creating a text file then pointing cron to that file or manually.

To set up manually

sudo crontab -e

To point cron to a text file

sudo crontab <filename>

Logically, preferably entered in the order of occurance. For example if you have a job that runs before another (in time) place that above.

Remember that the cron file or crontab must have entries in the following format

m h dom mon dow full path command

For example shutdown at 2:30PM ever day of week except weekends would be

30 14 * * 2,3,4,5,6 /sbin/shutdown

Another example run a script file (test.sh - located in /usr/local/myScripts folder) every monday at 2:00AM would be

0 2 * * 2 /usr/local/myScripts/test.sh

I had the same problem with cron, once and I remember reading in a forum that we need to delete the user's cron and restart the system then recreate it.

I had similar with a fresh UbuntuDDE install. I found answers in various sources (this one is probably the most relevant Ubuntu 18.04 - Dell XPS13 9370 no longer suspends on lid close). The issue is the laptop not going into "deep" sleep. Run this command

cat /sys/power/mem_sleep

And if you get the result below, then this is the issue.

[s2idle] deep

To change it, edit your grub file to add this text to the GRUB_CMDLINE_LINUX_DEFAULT line

mem_sleep_default=deep

Then update grub

sudo update-grub

and reboot. After reboot, run this again

cat /sys/power/mem_sleep

and confirm now that your result is

s2idle [deep]

Then you should be good to go.