If you run into this error it's a strong indicator that the Password Validation Plugin is installed.
The quick and dirty way to fix this is to uninstall the plugin. You will need to be the root user in the database.
# mysql -u root -p
Type your password, then uninstall the plugin:
mysql> uninstall plugin validate_password;
If you really want to dig in deeper you can play with the plugin configuration. You do that by logging into MySQL and running the following:
This will show you the Plugin table and the associated settings. You can manipulate any of the settings in the table by doing any of the following:
mysql> SET GLOBAL validate_password_length = 6; mysql> SET GLOBAL validate_password_number_count = 0; mysql> SET GLOBAL validate_password.policy = LOW;
Be forewarned that I tried resetting some of the values and had little luck until I removed the plugin. In reality, I didn't need the plugin. I use a random password generator for all my passwords.
To learn more about the Password Plugin Categories see this page: https://dev.mysql.com/doc/refman/5.7/en/validate-password-options-variables.html