cPanel default backup system may fail to create and save backup of your server and send you following message:
The backup was not able to be completed because timed out waiting for /bin/backup to finish
Possible cause of the problem
Any old backup process is still running in background on the server.
Login to your server as root via SSH and execute following command
# /usr/local/cpanel/bin/backup --force
Most probably it will show you following type message:
Backup process currently running. Pid: 5378
Backup log file: /usr/local/cpanel/logs/cpbackup/1377934812.log
Solution
We need to kill the current running backup process. Note the Pid from above and run following command. Change xxxx to Pid number that you have got from above.
# kill -9 xxxx
cPanel backup should now run normally. You can force to start a new fresh backup process using below command:
# /usr/local/cpanel/bin/backup --force