How to fix CR_AUTH_PLUGIN_CANNOT_LOAD (2059): Authentication plugin cannot be loaded in MySQL

Check the authentication plugin for the user account:

SELECT user, host, plugin FROM mysql.user WHERE user = 'your_username';

This shows which authentication plugin (mysql_native_password, caching_sha2_password, etc.) the user is configured to use.

The most reliable fix is updating your database drivers and client libraries:

For Python:

pip install --upgrade mysql-connector-python
# or
pip install --upgrade PyMySQL

For Node.js:

npm install mysql2@latest

For PHP:

# Ensure you have mysqlnd (native driver) enabled
php -m | grep mysqlnd

For Java:
Update your MySQL Connector/J to version 8.0.13 or later in pom.xml or build.gradle.

Modern connectors support caching_sha2_password authentication.

If updating clients is not possible, change the user's authentication plugin:

ALTER USER 'your_username'@'your_host'
IDENTIFIED WITH mysql_native_password BY 'your_password';
FLUSH PRIVILEGES;

Replace 'your_username', 'your_host', and 'your_password' with actual values. This allows older clients to connect.

If MySQL is installed in a non-standard location, specify the plugin directory:

Command line:

mysql --plugin-dir=/path/to/mysql/lib/plugin -u username -p

In my.cnf or my.ini:

[client]
plugin-dir=/usr/lib/mysql/plugin

Common plugin directory locations:
- Linux: /usr/lib/mysql/plugin or /usr/lib64/mysql/plugin
- macOS: /usr/local/mysql/lib/plugin
- Windows: C:\Program Files\MySQL\MySQL Server X.X\lib\plugin

To make all new users use mysql_native_password by default, edit MySQL configuration:

In my.cnf (Linux/macOS) or my.ini (Windows):

[mysqld]
default_authentication_plugin=mysql_native_password

Restart MySQL service:

# Linux
sudo systemctl restart mysql

# macOS
brew services restart mysql

# Windows
net stop MySQL80
net start MySQL80

This only affects newly created users. Existing users must be altered individually.

For MySQL 9.0+, mysql_native_password is a dynamically loadable plugin. Install it if missing:

Check if plugin file exists:

# Linux/macOS
ls -la /usr/lib/mysql/plugin/authentication_ldap_simple.so
ls -la /usr/lib/mysql/plugin/mysql_native_password.so

# Windows
dir "C:\Program Files\MySQL\MySQL Server 9.0\lib\plugin\mysql_native_password.dll"

If missing, reinstall MySQL client:

# Homebrew (macOS)
brew reinstall mysql-client

# APT (Ubuntu/Debian)
sudo apt-get install --reinstall mysql-client

# YUM (RHEL/CentOS)
sudo yum reinstall mysql-community-client