Fix MySQL "Access Denied for User" (Error 1045)

Error 1045 means MySQL rejected the login. The fix depends on which part failed — the password, the host the user is allowed from, or missing privileges. Here's how to find and fix it, plus the auth-plugin and case-sensitivity gotchas.

Read the error carefully

The message tells you a lot: Access denied for user 'app'@'localhost' (using password: YES) means the user, the host (localhost) and that a password was sent. using password: NO means no password was provided at all.

The exact wording narrows it down fast — match yours here, then go to the fix:

Cause 1: wrong password

The most common cause. Reset it (as root) and update your app config to match:

ALTER USER 'app'@'localhost' IDENTIFIED BY 'new_password';
FLUSH PRIVILEGES;

Cause 2: wrong host

A user defined as app@localhost can't connect from another IP. If your app connects over the network, create/grant the user for that host:

CREATE USER 'app'@'%' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON mydb.* TO 'app'@'%';
FLUSH PRIVILEGES;

Cause 3: missing privileges

The user exists and the password is right, but it has no rights on the database. Grant them as shown above, scoped to the specific database.

Verify the user

SELECT user, host FROM mysql.user WHERE user = 'app';
SHOW GRANTS FOR 'app'@'localhost';

1045 is always user + password + host. Confirm the password, confirm which host the user is allowed from, and confirm the grants.

Cause 4: wrong authentication plugin

MySQL 8 defaults new users to caching_sha2_password, which some older clients/drivers can't speak, producing what looks like a plain access-denied. If your app can't support the new plugin, switch the user to the legacy mysql_native_password plugin with an ALTER USER ... IDENTIFIED WITH mysql_native_password BY 'password' statement, then FLUSH PRIVILEGES.

Cause 5: leftover skip-grant-tables or case sensitivity

If the server was ever started with --skip-grant-tables for a manual fix and not restarted cleanly afterward, grants can end up inconsistent. Also remember usernames are case-sensitive on most systems — App and app are different users.

How to prevent 1045 errors

• Store credentials in environment variables/config, not hardcoded — makes rotating a leaked password fast.
• Grant the narrowest host you actually need (a specific IP) rather than % where possible.
• After any migration or restore, re-check that users and grants moved with the data — a dump can miss the mysql.user table.

Related errors

If the database service itself won't start, see fixing MySQL/MariaDB won't start. WordPress sites showing a database error from the same root cause are covered in fixing "Error establishing a database connection". phpMyAdmin login issues are covered in fixing phpMyAdmin access denied.

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