The World of MySQL & MariaDB

MySQL ‘Access denied for user’ Error: Causes & Fixes

Errors and Troubleshooting
目次

1. Introduction

The “mysql access denied for user” error is a common issue that MySQL users frequently encounter. This error means that the connection to the database was denied and requires proper configuration of settings and permissions.

What You’ll Learn From This Article

  • You will understand the cause of the error and be able to implement appropriate solutions.
  • You will learn how to efficiently handle MySQL configuration and user management with beginner-friendly steps.

Intended Audience

  • Beginners who have just started using MySQL
  • Intermediate users struggling with error troubleshooting
  • Technicians who want to understand the root cause of the problem
This article provides a comprehensive explanation covering the error details, causes, solutions, and preventive measures.

2. What the “Access denied for user” error means

Meaning of the error message

In MySQL, the “Access denied for user” error occurs when authentication fails. The typical format of this error is as follows:
ERROR 1045 (28000): Access denied for user 'username'@'hostname' (using password: YES)

Key parts of the error

  • 'username': the MySQL username in question
  • 'hostname': the host name that attempted the connection (e.g., localhost, IP address)
  • (using password: YES): shown when password authentication is being used
This error occurs due to issues related to user authentication or privileges.

Common situations where the error occurs

This error often occurs in cases such as the following:
  1. Immediately after creating a new user Occurs when privileges are not set correctly.
  2. Application connection information is incorrect Especially when using stored outdated credentials.
  3. Host restrictions are configured Connections from hosts not allowed are denied.

Additional notes for beginners

A “host” refers to the device or server attempting to connect to MySQL. For example, localhost refers to the computer you are currently working on.

3. Main Causes

Incorrect Username or Password

The most common cause is an incorrect username or password.

Common Mistakes

  • The configuration file contains incorrect credentials.
  • The application is using outdated credentials.

How to Check

Use the following command to verify that you can log in with the correct username and password.
mysql -u username -p
When prompted for a password, enter the correct one. If it’s wrong, the login will fail.

Insufficient User Privileges

In MySQL, access rights are set per user. If privileges are insufficient, access to the database is denied.

How to Verify Privileges

Use the following command to check the user’s privileges.
SHOW GRANTS FOR 'username'@'hostname';
If the required privileges are not granted, you need to grant the appropriate rights.

Host Name Mismatch

In MySQL, a user may be configured to allow connections only from specific hosts (e.g., localhost or an IP address). Consequently, if the host name does not match, the connection will be rejected.

How to Check Host Settings

SELECT Host, User FROM mysql.user WHERE User = 'username';
Running this command displays the list of hosts allowed for the specified user. If the current connecting host is not in the list, the connection will be denied.

MySQL Configuration Issues

Problems in MySQL’s configuration file (usually my.cnf or my.ini) can also cause errors. In particular, the bind-address setting can have an impact.

How to Verify Settings

Open the configuration file and check the bind-address entry.
bind-address = 127.0.0.1
In this case, remote connections are not allowed, so external access is denied. If you want to allow remote connections, change it to bind-address = 0.0.0.0 and restart MySQL.

4. Solution

Verify Username and Password

First, verify that the current credentials are correct.

Steps

  1. Run the following command and attempt to log in with the correct username and password.
mysql -u username -p
  1. If you cannot log in even after entering the correct password, you need to reset the password.

Resetting the Password

SET PASSWORD FOR 'username'@'hostname' = PASSWORD('new_password');

Configuring User Privileges

Check that the necessary privileges are granted, and if any are missing, assign the appropriate privileges.

Check Privileges

SHOW GRANTS FOR 'username'@'hostname';

Grant Privileges

GRANT ALL PRIVILEGES ON database_name.* TO 'username'@'hostname';
FLUSH PRIVILEGES;
This grants the user all privileges and applies the changes.

Correcting the Hostname

If the host configuration is causing errors, you need to set the appropriate host.

Check Host Settings

SELECT Host, User FROM mysql.user WHERE User = 'username';

Modify Host Settings

UPDATE mysql.user SET Host='%' WHERE User='username';
FLUSH PRIVILEGES;
% allows connections from any host. However, because this poses a security risk, it is recommended to specify a particular IP address when appropriate.

Changing MySQL Configuration

Edit the configuration file (my.cnf or my.ini) to set appropriate connection restrictions.

Edit Configuration File

For Linux environments:
sudo nano /etc/mysql/my.cnf
For Windows environments:
C:ProgramDataMySQLMySQL Server X.Xmy.ini
(X.X varies depending on the MySQL version.)

Check bind-address Setting

bind-address = 127.0.0.1
With this setting, connections are allowed only from localhost. To permit remote connections, change it as follows.
bind-address = 0.0.0.0

Restart MySQL to Apply Changes

sudo systemctl restart mysql
Or (on Windows):
net stop MySQL
net start MySQL
This method can resolve many “Access denied for user” errors. Next, review the Frequently Asked Questions (FAQ).

5. FAQ (Frequently Asked Questions)

Q1: What should I do if the error does not get resolved?

A1: Please check the error log.

Checking MySQL’s error log is effective for identifying the cause of the error.

Linux:

sudo cat /var/log/mysql/error.log

Windows:

The default error log path is one of the following:
C:ProgramDataMySQLMySQL Server X.Xerror.log
Check the log and address the issue based on the specific error messages.

Q2: Why does only a specific user encounter the error?

A2: The host settings or privileges of the affected user may be the cause.

Use the following command to check the privileges of the affected user.
SHOW GRANTS FOR 'username'@'hostname';
Also, verify whether the host settings are correct.
SELECT Host, User FROM mysql.user WHERE User = 'username';
If the host settings are incorrect, correct them appropriately.
UPDATE mysql.user SET Host='%' WHERE User='username';
FLUSH PRIVILEGES;

Q3: How do I reset it if I forget my login credentials?

A3: Start MySQL in safe mode and reset the password.

Linux:

sudo systemctl stop mysql
sudo mysqld_safe --skip-grant-tables &
mysql -u root
Then, reset the password with the following command.
UPDATE mysql.user SET authentication_string=PASSWORD('new_password') WHERE User='root';
FLUSH PRIVILEGES;
EXIT;
Restart MySQL.
sudo systemctl restart mysql

Windows:

  1. Open Command Prompt with administrator privileges and start MySQL in safe mode.
net stop MySQL
mysqld --skip-grant-tables
  1. In another Command Prompt, connect to MySQL and reset the password.
mysql -u root
UPDATE mysql.user SET authentication_string=PASSWORD('new_password') WHERE User='root';
FLUSH PRIVILEGES;
EXIT;
  1. Restart MySQL.
net start MySQL
You can reset a forgotten password using this procedure. This FAQ section covered troubleshooting steps for unresolved errors and answered common questions. Finally, review the article summary.

6. Summary

In this article, we explained in detail the “Access denied for user” error that occurs in MySQL. This error often occurs due to incorrect credentials, insufficient privileges, host configuration errors, or MySQL misconfigurations.

Key Points of This Article</h3

  1. Identify the cause of the error
  • Verify that you are not using an incorrect username or password.
  • Check privileges with SHOW GRANTS FOR 'username'@'hostname';.
  • Check host settings with SELECT Host, User FROM mysql.user WHERE User = 'username';.
  1. Apply the appropriate solution
  • Reset the password (using the SET PASSWORD command).
  • Modify privileges with the GRANT ALL PRIVILEGES command.
  • Correct the bind-address setting to allow remote connections.
  1. If the issue persists, check the error log
  • Linux: /var/log/mysql/error.log
  • Windows: C:ProgramDataMySQLMySQL Server X.Xerror.log

Best Practices to Prevent Recurrence

  • Maintain proper user management
  • Assign appropriate privileges to each required user and remove unnecessary accounts.
  • Clarify host settings
  • '%‘ is a security risk because it permits access from any host; restrict it to specific hosts.
  • Perform regular backups
  • To prevent issues caused by misconfigurations, make it a habit to back up using mysqldump.

Conclusion

The “Access denied for user” error can seem daunting for beginners, but following the steps in this article will resolve most issues. If problems persist, check the error log and review your configuration and privileges again.