How to Fix Authentication Plugin Error in MySQL

The MySQL authentication plugin error occurs when the client and server use incompatible authentication methods. Fix it by changing the user's authentication plugin to mysql_native_password using the command ALTER USER 'username'@'host' IDENTIFIED WITH mysql_native_password BY 'password'; and then flushing privileges.

Why This Happens

This error happens because MySQL server and client use different authentication plugins. For example, MySQL 8.0 uses caching_sha2_password by default, but some clients only support mysql_native_password. When you try to connect, MySQL rejects the login due to this mismatch.

sql

mysql -u root -p
-- Then trying to connect to a user created with default plugin
CREATE USER 'user1'@'localhost' IDENTIFIED BY 'password';
-- This user uses caching_sha2_password by default

mysql -u user1 -p
-- Connection fails with error:

Output

ERROR 2059 (HY000): Authentication plugin 'caching_sha2_password' cannot be loaded: client does not support authentication plugin

The Fix

Change the user's authentication plugin to mysql_native_password which is widely supported. This is done by running an ALTER USER command and then flushing privileges to apply changes.

sql

ALTER USER 'user1'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';
FLUSH PRIVILEGES;

Output

Query OK, 0 rows affected (0.01 sec)

-- Now connecting as user1 works without error:
mysql -u user1 -p
Welcome to the MySQL monitor. Commands end with ; or \g.

Prevention

To avoid this error in the future, always specify the authentication plugin when creating users if you know your client compatibility. Keep your MySQL client updated to support the latest plugins. Also, check your MySQL server version and client compatibility before connecting.

• Use mysql_native_password for older clients.
• Update clients to support caching_sha2_password.
• Test connections after user creation.

Related Errors

Other similar errors include:

• ERROR 1045 (28000): Access denied for user - usually wrong password or user host mismatch.
• Client does not support authentication protocol requested by server - similar plugin mismatch.
• Authentication plugin 'sha256_password' cannot be loaded - missing client support for that plugin.

Fixes usually involve updating client, changing user plugin, or adjusting server settings.

Key Takeaways

Authentication plugin errors happen due to client-server plugin mismatches.

Fix by changing user plugin to mysql_native_password with ALTER USER command.

Flush privileges after changes to apply them immediately.

Keep MySQL clients updated to support latest authentication plugins.

Specify authentication plugin explicitly when creating new users.