2024 ทำไม error establishing a database connection wordpress

The most common cause of "error establishing a database connection" in WordPress is your server running out of memory. When the server runs out of memory, MySQL will crash. The best solution is to upgrade to a server with more memory.

In addition to increasing your server's memory, you may want to reduce your WordPress site's memory usage.

You can confirm that your server is running out of memory by looking for the message "Out of memory" in the log file /var/log/syslog.

Another cause of "error establishing a database connection" is a full disk. You should check your server's disk space. If it is full, then you should either upgrade to a larger size or carefully delete unnecessary files.

If you have verified that your server is not running out of memory or disk space, you may have incorrect database credentials in your WordPress app's wp-config.php file. You should confirm that the database information in that file is correct.

พอเปิดเข้าเวบมันขึ้น "Error establishing a database connection" เป็นบล็อคที่ทำจาก wordpress สาเหตุอาจเกิดจาก User Name กับ Password และ MySQL database username ที่ติดต่อกับฐานข้อมูลไม่ตรงกัน วิธีแก้ให้เข้าไปแก้ที่ ไฟล์ wp-config.php โดยแก้ที่ User Name , Password และ MySQL database username ลองเช็คดูว่ามันตรงกันหรือเปลี่ยนไปหรือไม่ ที่ผมเจอคือ MySQL database username ไม่ตรงกับที่ตั้งไว้สงสัยคงมีใครมาเปลี่ยนแน่ๆๆๆ

“Error Establishing a Database Connection” is an error telling you that your WordPress website can’t connect to its database. It may seem hard to fix, but fortunately, there are only a handful of issues causing it, and with a bit of investigation and troubleshooting, you can easily resolve the problem.

This guide will explain what “Error Establishing a Database Connection” means, and outline the most common causes and how to fix them.

What does WordPress’ “Error Establishing a Database Connection” mean?

The error “Error Establishing a Database Connection” in WordPress indicates that the connection between WordPress and its database has failed due to various potential reasons.

Before looking into the error, we need to understand how WordPress works. Like most CMS (Content Management System) applications, it consists of two integral parts – files and a database.

The files are the website’s frame and contain the core functionalities of WordPress, the media, themes and plugins.

On the other hand, the database contains the website’s custom settings and unique content. All the pages, posts, text and design are recorded as entries in the tables.

The files communicate with the database through various PHP and MySQL functions and extract data visualized on the web pages.

Therefore, when your website fails to connect to the database, it can’t retrieve the data required to display the pages. WordPress warns you of the problem by displaying the message “Error Establishing a Database Connection”, as seen in the image below.

What are the most common causes of “Error Establishing a Database Connection”?

There are a few different scenarios in which the error appears. The most common ones include:

• Wrong database settings in the configuration file – Incorrect database credentials are arguably the most common reason for a disrupted database connection. If the database name, username, password or hostname are wrong, the website won’t connect to the database and will return “Error establishing database connection”.
• Insufficient database user privileges – Another reason why the error occurs is if the database user doesn’t have sufficient privileges, even if the credentials are correct. The user must have permission to execute all types of MySQL operations onto the database.
• Corrupted database tables – WordPress is a highly-dynamic system, and each time you make changes to your website, the database’s tables are modified. Adding or deleting plugins and themes creates new tables or deletes existing ones, new pages add new entries, etc. With so many MySQL operations being conducted, occasionally, the tables may become corrupted, which could lead to another variation of the “Error establishing database connection” – “One or more database tables are unavailable”.
• Incorrect website URLs – On rare occasions, the “Error establishing a database connection” could be caused by incorrect website URLs.
• Corrupted WordPress files – Another reason why you see the “Error establishing a Database Connection” message is that your website’s WordPress core files are corrupted. This could stem from a malware infection, failed update, or incomplete file transfer while moving your site manually.
• The database server is down or overloaded.

How to Fix “Error Establishing a Database Connection”

At first glance, the error sounds quite intimidating and hard to resolve. However, it usually boils down to a few key settings, which can be easily checked and fixed.

How to Fix “Error Establishing a Database Connection” Video Tutorial

Inspect the wp-config.php File of your WordPress website

The settings for the database are stored in the configuration file of every WordPress installation. It is called wp-config.php and is located in the root directory of your website.

To check the file, log into the website folders via or your hosting’s panel. If you are a SiteGround user, navigate to Site Tools > Site > File Manager.

The root folder of every website is the directory yourdomain.com/public_html. In our example, the website name is sg-testing.com, so the folder is sg-testing.com/public_html.

Before making any changes, it’s best to keep a backup of the file just in case. To do that, right-click on the file, select Copy, and rename the copied version to wp-config-backup.php.

After creating the backup copy, select the file wp-config.php, and choose Edit.

The database name, user, password and host are defined in the following lines of code:

// ** Database settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define( 'DB_NAME', 'database_name_here' );
/** Database username */
define( 'DB_USER', 'username_here' );
/** Database password */
define( 'DB_PASSWORD', 'password_here' );
/** Database hostname */
define( 'DB_HOST', 'localhost' );

The values of each setting must match the existing database, user and password in the MySQL server of the website. After applying the changes, press the Save (floppy disk) icon.

Set the correct database hostname

The MySQL server is defined by the line of code:

define( 'DB_HOST', 'localhost' );

Typically, the database host is on the same server as the website’s files. Therefore, the value is “localhost” or “127.0.0.1” and the entire line will read:

define( 'DB_HOST', 'localhost' );

or

define( 'DB_HOST', ‘127.0.0.1’ );

If you’ve set a remote database host, you must replace these values with the correct hostname of the remote server.

Set the correct database name

After the host has been established, check the database details in the MySQL server. SiteGround users can easily access the MySQL database settings from Site Tools > Site > MySQL.

To compare the settings from the wp-config.php file with the MySQL database details more easily, open the MySQL section in a new browser tab by right-clicking on it and selecting Open in a New Tab.

The existing databases on the MySQL server are listed in the Databases tab under Manage Databases.

The database listed there must match the one defined in the wp-config.php file.

Copy the database’s name from MySQL > Databases and paste it in the line of code in wp-config.php:

define( 'DB_NAME', 'database_name_here' );

Set the correct database username

To see the user for the database, click on the link under the Users column of the database.

A popup window will appear listing all users with privileges to modify the website’s database. Highlight the username under the User column and copy it.

Go back to editing the wp-config.php file and paste the name in the line:

define( 'DB_USER', 'username_here' );

If there is no user attached to the database, there will be no link under the Users column. Click on the Add New User icon under the Actions column to add an existing user to the website’s database.

In the popup window, select one of the names from the Users drop-down menu, check the radio button All Privileges, and press Confirm.

After the user is attached to the database, you can copy their name and paste it in the wp-config.php file.

If there are no existing users, open the section Site Tools > Site > MySQL > Users. You can create a new user by pressing the button Create User.

IMPORTANT! Keep in mind that you can’t choose the database’s username. It will be automatically generated by the system.

The new username will appear under the Manage Users section in the Users tab. Click on the icon Add new database to attach the user to the website’s database.

In the pop-up window, select the website’s database, check the radio button All privileges, and hit Confirm.

You can then copy the new username and paste it in the respective line in wp-config.php.

Set the correct database user’s password

After adding the user in wp-config.php, you must ensure that the user’s password in the file matches its counterpart in MySQL. Copy the password string from the line in wp-config.php:

define( 'DB_PASSWORD', 'password_here' );

After the password is copied, go back to Site > MySQL > Users, press the kebab menu, and select Change Password.

Paste the password in the New password field and hit Confirm.

The error should disappear when reloading the website if all credentials are set correctly.

Check if the Database User has the Correct Privileges

To check the user’s privileges, go to Site Tools > Site > MySQL > Users, and find the user in the section Manage Users. Click on the link under the Database Access column, which opens a new pop-up window.

Press the Manage Access icon to open a new window where the access options are managed.

To set all necessary permissions, select the radio button All Privileges and click on the button Confirm.

Repair the Database

If your database is damaged, you need to repair it, and thankfully, WordPress has a built-in repair mode.

To activate it, you need to edit your website’s wp-config.php file via or your hosting control panel.

SiteGround users can edit the file by navigating to Site Tools > Site > File Manager. The file is located in the website’s root directory, which is yourdomain.com/public_html (where you need to replace yourdomain.com with your own domain).

Select wp-config.php and press Edit.

Just above the line “/* That’s all, stop editing! Happy publishing. */”, add the following code:

define('WP_ALLOW_REPAIR', true);

Confirm the changes by pressing the Save icon.

To load repair mode, open the page https://yourdomain.com/wp-admin/maint/repair.php in your browser, where yourdomain.com is replaced with your website’s name. For example, our name is sg-testing.com, so the address would be https://sg-testing.com/wp-admin/maint/repair.php.

Choose between the two options Repair Database and Repair and Optimize Database, and once the maintenance is over, reload your website’s homepage. Once you confirm that the error is fixed, remove the code you added in wp-config.php so no one else can run repair mode.

Inspect the WordPress Site URL in the Database

The error will prevent you from logging into the dashboard where the website’s URL is set. However, you can use phpMyAdmin to edit the tables where these settings are defined.

SiteGround users can reach the tool by navigating to Site Tools > Site > MySQL > PHPMYADMIN > ACCESS PHPMYADMIN.

Click on the website’s database in the column on the left and open the wp_options table.

Note that wp_ is the default WordPress table prefix, but in most cases, the prefix for your site will be custom.

The website URLs are defined in the options siteurl and home. Press Edit on each, set the correct website URL in the option_value field, and confirm the change with the button Go.

Restore a Backup of the Site

If you encountered the error after a manual transfer, make sure to export a new full website backup from the previous hosting and import it into the new hosting again.

If the website has not been transferred and the error suddenly appears, your best choice is to restore the website from a recent backup. See this tutorial for SiteGround’s Backup tool.

Contact the Web Hosting Provider

The solutions described above work if the issue stems from the website’s configuration. However, WordPress may fail to connect to the database if the MySQL server is overloaded or under maintenance.

If you manage your own server, consider restarting the MySQL service to clear any stuck database queries overloading it.

Users with managed hosting don’t have this type of access. Contact your provider’s support team so they can check the status of the server and resolve the problems from their side.

Summary

“Error establishing a database connection” is a widespread WordPress error that you are likely to encounter every once in a while. In a nutshell, it informs you that your website can’t connect with its database.

During this period, your website is not accessible, and you need to repair it before you lose substantial traffic. But don’t worry, there are only a small number of causes, and with a bit of troubleshooting, they can be easily ironed out.

This guide has outlined the most common causes of the error. By following the instructions carefully, you’re sure to get your website back online in no time.