mysql + homebrew
Basically you will have to perform some actions manually, however- your database data won't be deleted like in solution below

Go to my.cnf file and in section [mysqld] add line:

default-authentication-plugin=mysql_native_password

Login to mysql server from terminal: run mysql -u root -p, then inside shell execute this command (replacing [password] with your actual password):

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '[password]';

exit from mysql shell with exit and run brew services restart mysql.

Should work.

Quick fix (destructive method)
Quick fix for non-homebrew installs:

Apple Logo > System Preferences > MySQL > Initialize Database, then type your new password and select 'Use legacy password'

After restart you should be able to connect. Do it only on fresh installs, because you may lost your db tables otherwise.

my.cnf
The my.cnf file is located in /etc/my.cnf on Unix/Linux

Alternatives
For those who is still struggling with Sequel Pro problems: Sequel Pro was a great product, but with tons of unresolved issues and last release being dated to 2016 perhaps it's a good idea to look for some alternatives. There is a fork of SequelPro called SequelAce that seems to be pretty stable and up-to-date, it keeps similar functionality, similar look and feel, yet at the same time it is devoid of old Sequel Pro problems. Basically I have faced the same while working on ios app development agency (https://enterprise.affle.com/ios-app-development) .Before troubleshooting the error, we recommend taking a WordPress site backup. Many of the recommendations below involve manipulating information in your database, so you don’t want to make things worse. You should always backup before trying to fix things on your WordPress site, no matter how tech-savvy you think you are.

You can use a popular WordPress backup plugin such as VaultPress or WP Time Capsule to backup your files and database.

If you are a Kinsta user, you can take advantage of our one-click backup feature. Click into your WordPress site in MyKinsta, click on “Backups” and then on “Back up now.”
Hope this will help everyone.

Database Name
// ** MySQL settings ** //

/** The name of the database for WordPress */

define('DB_NAME', 'xxxxxx');
MySQL database username
/** MySQL database username */

define('DB_USER', 'xxxxxx');
MySQL database password
/** MySQL database password */

define('DB_PASSWORD', 'xxxxxxxxx');
MySQL hostname (server)
/** MySQL hostname */

define('DB_HOST', 'localhost');
To access your wp-config.php file, you can connect to your site via SFTP and browse to the root of your site. Or, if you are using cPanel, you can click on “File Manager,” browse to the root of your site, and right-click to edit the file.

You can also verify this is the correct database by ensuring it contains your WordPress site’s URL. To do this, click on the database and then click into the wp_options table (this might be slightly different for security purposes, such as wpxx_options). At the top of the table, you will see values for your site’s URL and name. If these match your current site, you can rest assured you are in the right place.