Cron service not running: causes and fixes

What the "Cron service not running" Error Means

The error "cron service not running" (or its Russian equivalent "служба cron не запущена") means that the cron daemon—the system service responsible for executing scheduled tasks—is not currently active. Without a running daemon, crontab files where you add jobs (e.g., via crontab -e) will not be executed. You may encounter this issue when:

• Tasks that were supposed to run do not execute.
• Attempting to add a job via crontab -e displays a warning.
• The command systemctl status cron (or service cron status) shows a status of inactive (dead) or stopped.
• Logs (/var/log/syslog or journalctl -u cron) lack entries indicating task execution.

Common Causes

1. The service was not started after installation. In some distributions (e.g., minimal installations), the cron service is not activated by default.
2. The service was manually stopped. An administrator or script may have executed systemctl stop cron.
3. Service failure. The cron daemon may have terminated unexpectedly due to corrupted configuration (/etc/crontab, files in /etc/cron.d/) or insufficient system resources.
4. The service is not enabled for autostart. After a system reboot, cron does not start automatically.
5. Use of an outdated init system (SysVinit) with missing symbolic links. In systems using the old init, necessary links in /etc/rc?.d/ might be absent.

Method 1: Starting and Enabling Autostart via systemd (Modern Systems)

Most modern distributions (Ubuntu 16.04+, Debian 8+, CentOS 7+, RHEL 7+) use systemd.

1. Check the service status:

   systemctl status cron
   

   
   Or, if the service is named crond (common in RHEL/CentOS/Fedora):

   systemctl status crond
   

   
   Look for the Active: line in the output. If it says inactive (dead) or failed, the service is not running.
2. Start the service immediately:

   sudo systemctl start cron
   

   
   Or for crond:

   sudo systemctl start crond
   

3. Enable autostart for the service:

   sudo systemctl enable cron
   

   
   This command creates symbolic links to ensure cron starts on every system boot. For crond, use sudo systemctl enable crond.
4. Restart the service to apply changes (if configurations were modified):

   sudo systemctl restart cron
   

5. Verify the service is active and enabled:

   systemctl is-active cron && echo "Active" || echo "Not active"
   systemctl is-enabled cron && echo "Enabled" || echo "Not enabled"
   

Method 2: Management via the service Utility (Universal Wrapper)

The service utility is a wrapper that automatically detects whether systemd or classic SysVinit is used in the system and calls the appropriate tool. It can be convenient for writing scripts that run on different systems.

1. Check status:

   sudo service cron status
   

2. Start the service:

   sudo service cron start
   

3. Enable autostart (for SysVinit):

   sudo update-rc.d cron defaults
   

   
   Note: On systemd systems, the command sudo service cron enable typically just calls systemctl enable and works identically to Method 1.
4. Stop the service:

   sudo service cron stop
   

Method 3: Manual Management for SysVinit (Older Systems)

Very old distributions (e.g., CentOS 6, Debian 7) or specialized containers may use the classic init.

1. Check for an init script:

   ls -l /etc/init.d/cron
   

   
   If the file is missing, the cron service is likely not installed.
2. Start the service directly:

   sudo /etc/init.d/cron start
   

3. Enable autostart via update-rc.d (Debian/Ubuntu) or chkconfig (RHEL/CentOS 6):
   • For Debian/Ubuntu:

     sudo update-rc.d cron defaults
     

   • For RHEL/CentOS 6:

     sudo chkconfig cron on
     

Method 4: Diagnostics if the Service Fails to Start or Crashes Immediately

If start commands do not succeed and status shows failed:

1. View systemd logs for the service:

   sudo journalctl -u cron -b --no-pager
   

   
   Key flags: -u cron (filter by unit), -b (logs since last boot). Look for lines containing Failed or Error.
2. Check the integrity of cron configuration files:
   • Main file: /etc/crontab.
   • Directories: /etc/cron.d/, /etc/cron.hourly/, /etc/cron.daily/, /etc/cron.weekly/, /etc/cron.monthly/.
   • Check syntax. Common errors: incorrect delimiter (5 fields in /etc/crontab, not 6), missing user field in a line, non-existent command path.
   • Test syntax (for some versions):

     sudo crontab -l -u root 2>/dev/null || echo "Check /etc/crontab manually"
     

3. Ensure there is free disk space:

   df -h /
   

   
   If the disk is full (>95%), the daemon may fail to start.
4. Check for conflicts with other software. Sometimes packages like anacron can affect behavior. Try temporarily renaming the /etc/cron.d/ directory and restarting the service to test.

Prevention

• Regularly check the service status after system updates or configuration changes.

  systemctl is-active cron || echo "Cron is down!"
  

• Do not edit system crontab files (/etc/crontab, /etc/cron.d/*) directly without first validating syntax. Use crontab -e for user-specific jobs.
• Before rebooting after configuring cron, ensure the service is enabled for autostart: systemctl is-enabled cron.
• Set up monitoring. Add a simple cron status check to your monitoring system (Zabbix, Nagios, Prometheus node_exporter) or to a script that runs more frequently than once a minute.
• Monitor space on the system partition. A full root partition (/) is a common cause of system service failures.