Access denied for user root'@'localhost

Every time apt-get upgrade upgrades my local MySQL instance on my Ubuntu laptop I get the following error:

(1698, "Access denied for user 'root'@'localhost'") 

The fix each time is the following, so here it is for me next time save me wasting time googling the error every time.

sudo mysql -u root use mysql; update user set plugin='mysql_native_password' where User='root'; flush privileges; 

And with that all is well again!

Success? 🎉