After upgrading an instance of MySQL to 5.7 I was unable to login and had several of the following entries in the error log.
[Warning] User entry 'username'@'hostname' has an empty plugin value. The user will be ignored and no one can login with this user anymore.
This is explained the the release notes. Here’s the process I followed to fix this.
# Identify the path to mysqld_safe ps -e | grep mysqld # Stop mysql sudo /sbin/service mysql stop # Start with --skip-grant-tables sudo /usr/bin/mysqld_safe --skip-grant-tables # Run mysql_upgrade sudo mysql_upgrade -h 127.0.0.1 -u root -p # Restart mysql sudo /sbin/service mysql restart