Ubuntu Software Center cannot proceed when applying changes

If we had the this issue, we can try the following. 
sudo lsof /var/lib/dpkg/lock

From the above command we can know the PID of the process causing dpkg to lock. Then we do
sudo kill -TERM <PID>

Next, we do
sudo dpkg –configure -a

and waited for the result. After that we can do
sudo apt-get update && sudo apt-get upgrade