Answer by Christopher Gonzalez Gonzalez for Why crontab scripts are not working?

In 16.04, if you have this error in syslog

(CRON) error (can't fork)

try:

systemctl status cron.service

In the result:

Tasks: num_task (limit: 512)

If num_task is close to the limit use:

systemctl set-property cron.service TasksMax=new_max

Replace new_max with a suitable value.