Recently I was having issues with cron not executing between the times of 10pm to 9am and when I didn’t access the server for an extended period of time. The issue I found was that my server was hibernating/sleeping at those times and cron doesn’t execute if that happens. My ubuntu server doesn’t have a GUI so everything needs to be configured in the command line. So here is what I did.
edit the grub file:
$ sudo nano /etc/default/grub
Add the kernel options “acpi=off apm=off” to the GRUB_CMDLINE_LINUX_DEFAULT:
$ sudo update-grub
Reboot your computer.
turn off ubuntu server hibernation