How to fix ERROR 1045: Access denied for user in MySQL

Double-check the credentials you are using. MySQL is case-sensitive for usernames and passwords are case-sensitive by default. If your password contains special characters like @, $, or &, wrap it in single quotes when passing via command line:

mysql -u root -p'S0me$pecial@Pass' -h localhost

If you are unsure of the password, you may need to reset it using safe recovery mode (see Step 3).

Connect to MySQL with an account that has admin privileges (or using recovery mode) and check if the user exists and from which hosts they can connect:

SELECT user, host FROM mysql.user WHERE user = 'username';

MySQL requires an exact match between the hostname in the connection string and the host listed in the user table. For example, user'@'localhost' cannot connect from 127.0.0.1, and vice versa. If the user does not exist, create it:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON database.* TO 'username'@'localhost';
FLUSH PRIVILEGES;

To allow connection from any host, use '%' as the host:

CREATE USER 'username'@'%' IDENTIFIED BY 'password';

MySQL 8.0 changed the default authentication plugin from mysql_native_password to caching_sha2_password. If you are connecting with a client that does not support the newer plugin, you will see Error 1045. Check the current plugin for your user:

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

If the plugin is caching_sha2_password and your client does not support it, change it to mysql_native_password:

ALTER USER 'username'@'hostname' IDENTIFIED WITH mysql_native_password BY 'password';
FLUSH PRIVILEGES;

If you are completely locked out, you can restart MySQL in safe mode to bypass authentication:

1. Stop the MySQL server:

sudo systemctl stop mysql
# or on macOS:
sudo /usr/local/mysql/support-files/mysql.server stop

2. Edit /etc/mysql/my.cnf or /etc/my.cnf and add the following under [mysqld]:

skip-grant-tables
skip-networking

3. Start MySQL:

sudo systemctl start mysql
# or on macOS:
sudo /usr/local/mysql/support-files/mysql.server start

4. Connect without password:

mysql -u root

5. Flush privileges and set a new password:

FLUSH PRIVILEGES;
ALTER USER 'root'@'localhost' IDENTIFIED BY 'new_secure_password';

6. Remove the skip-grant-tables and skip-networking lines from my.cnf and restart MySQL normally.

After creating a user or modifying permissions, you must flush the in-memory privilege cache:

FLUSH PRIVILEGES;

Verify the user has the necessary privileges:

SHOW GRANTS FOR 'username'@'hostname';

If no privileges are shown, grant them:

GRANT ALL PRIVILEGES ON *.* TO 'username'@'localhost';
FLUSH PRIVILEGES;

For application-specific users, grant only the minimum required privileges:

GRANT SELECT, INSERT, UPDATE, DELETE ON myapp_database.* TO 'app_user'@'localhost';
FLUSH PRIVILEGES;