I got this error earlier when I was connecting to mySQL using Visual Studio, and I did reset my password. I do not know why I got this again when I am using mySQL command line. I just searched for how to reset password, and it works fine again.
This is how to reset password in mySQL:
ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass';Reference: MySQL Reference Manual - How to reset root password?