dpkg: error: dpkg frontend is locked by another process code example

Example 1: dpkg: error: dpkg frontend lock was locked by another process with pid 4368

sudo rm /var/lib/dpkg/lock-frontend
sudo dpkg --configure -a

Example 2: dpkg: error: dpkg frontend lock is locked by another process

First, find out the id of the process that is holding the lock file:

lsof /var/lib/dpkg/lock-frontend

The above command will give you the PID of the processes using the lock files. Use this PID to kill the process:

sudo kill -9 PID

Now you can remove the lock and reconfigure dpkg:

sudo rm /var/lib/dpkg/lock-frontend
sudo dpkg --configure -a

Example 3: why upgrade ubuntu then frequently shows this message "It iwating for cache lock: Could not get lock /var/lib/dpkg/lock.frontend.

It iwating for cache lock: Could not get lock /var/lib/dpkg/lock.frontend.