Ubuntu 18.04 - MySQL - This installation of MySQL is already upgraded to 5.7.26 OR 5.7.27 OR 5.7.28, use --force if you still need to run mysql_upgrade

While upgrading to mysql 5.7.26 / 5.7.27 / 5.7.28, system hung with message

This installation of MySQL is already upgraded to 5.7.26 / 5.7.27 / 5.7.28, use --force 
if you still need to run mysql_upgrade 

Then I interrupted the installation using Ctrl + C

After upgrading to mysql 5.7.26 / 5.7.27 / 5.7.28, when system suggested package upgrades, I tried to upgrade the system using

sudo apt upgrade

while upgrading the system it suggested me to run the command

sudo dpkg --configure -a

While doing the system hung up again with the same message

This installation of MySQL is already upgraded to 5.7.26 / 5.7.27 / 5.7.28, use --force 
if you still need to run mysql_upgrade 

After struggling a lot, I found the solution here

Briefly, the solution is

Edit the file /var/lib/dpkg/info/mysql-server-5.7.postinst

sudo nano /var/lib/dpkg/info/mysql-server-5.7.postinst

At line # 370, comment the echo ALTER statement which would like  

#echo "ALTER USER 'root'@'localhost' IDENTIFIED WITH 'auth_socket';"                 >> "$initfile" 

Run dpkg configure again and the problem will be solved.

sudo dpkg --configure -a