cPanel uses a script called upcp to automatically update cPanel software. cPanel update script is running once a day via crontab and once it is completed, crontab will automatically send an email to the vps server administrator.
However, sometimes, you can get this error message:
cPanel Update (upcp) is already running. Please wait for the previous upcp to complete, or kill off all upcp processes and try again. You may wish to use ‘–force’ at /scripts/upcp line 48.
OR
cPanel Update (upcp) is already running. Please wait for the previous upcp to complete, or kill off all upcp processes and try again. You may wish to use ‘–force’
OR
If you try to update cPanel manually by clicking on "Update Server Software" link in cPanel WebHost Manager (WHM) yu may get the same cPanel error.
This happens cause another process is using upcp cPanel update script same moment. Simply kill the defunct upcp process using the following command to determine the process ID (pid) of the upcp process:
ps aux | grep upcp
If it is 12345, then use the following command to send the kill term signal to close cPanel update upcp script.
kill -9 12345
Replace the '12345' with the process ID (pid) for upcp. Sometimes, upcp appears defunct, and cannot be killed. Then try to kill the crond process.
Determine which pid is the crond with this command:
ps aux | grep crond
Note: In some system, you may have to use CROND (capital) instead of crond.
Then kill the running process with the same command:
kill -9 PID
After killing crond process, you will have to start crond daemon again using following command:
service crond start