Some Plesk automatic activities are not working: Job 'cron.daily' locked by another anacron - skipping

Symptoms

• Plesk does not check for updates automatically despite the option Tools & Settings > Updates > Automatically install Plesk updates (Recommended) is enabled.

• Logs for domains are also not rotated.

• Plesk license is not automatically renewed.

• Scheduled backups do not start.

• In /var/log/cron the following errors can be found:

  CONFIG_TEXT: Jul 7 10:01:01 ip-0-0-0-0 anacron[26504]: Job `cron.daily' locked by another anacron - skipping
  Jul 7 10:01:01 ip-0-0-0-0 anacron[26504]: Job `cron.weekly' locked by another anacron - skipping

Cause

Cron processes got stuck.

Resolution

1. Connect to the server via SSH

2. Find all running cron processes:

   # ps aux | grep cron
   root 1233 0.0 0.0 19064 968 ? Ss 2016 0:00 /usr/sbin/anacron -s
   root 1608 0.0 0.0 9208 1300 ? SN 2016 0:00 /bin/bash /usr/bin/run-parts /etc/cron.daily

3. Finish them using the following command:

   # kill -9 1233 1608

4. Restart crond service:

   # service crond restart