How to Fix the 503 Service Unavailable Error in WordPress

Encountering errors when accessing your WordPress website can be a headache for website owners. While solutions for some common errors can be easily found online, the 503 error can be particularly perplexing as it doesn’t provide much information, leaving many webmasters at a loss.

This article will help you understand the most common causes of the 503 error in WordPress. When troubleshooting the error, you’ll need to be systematic and follow a series of steps to identify the root cause.

In this guide, we’ll cover what the 503 error is and how it typically appears. Then, we’ll walk through six steps to troubleshoot it.

What is a 503 Error?

When you encounter a 503 error, it indicates that the relevant server is unavailable. This could be because the server is busy or undergoing maintenance. Unlike other similar error codes, 503 signifies that your website is online and running, but currently inaccessible.

What’s frustrating is that this particular error provides very little information. Most of the time, it simply displays a “Service Temporarily Unavailable” message. It’s like calling a restaurant and being told they’re not taking customers right now, but refusing to say when they will be again.

If you’re lucky, the 503 error code is because your WordPress website is under maintenance. When you update plugins, themes, or core software, WordPress briefly sets your website to maintenance mode:

WordPress Maintenance Mode

Usually, this timeout is very short, and no one will notice it. However, the 503 error can still occur in other situations, and you’ll face a bigger problem to deal with. After all, not only will users be unable to access your website, but you’ll also lose access to the WordPress admin dashboard. This means you can’t update your website in any way, and you’ll need to delve into its files to troubleshoot.

503 Error Variations

The 503 error can appear in many ways. However, almost every variation is accompanied by the 503 code, making it easy to identify.

Here are some variations you might encounter, depending on your server configuration and browser:

• 503 Service Unavailable
• 503 Service Temporarily Unavailable
• HTTP Server Error 503
• HTTP Error 503
• Error 503 Service Unavailable

Regardless of the error code you encounter, it means you need to address it quickly before it negatively impacts your users.

How to Fix the 503 Error in WordPress

Since you often can’t pinpoint the cause of the 503 error in any given situation, you need to troubleshoot it step by step. The following six steps each cover a solution designed to address different error causes.

After completing each step, take a moment to return to your website to see if the 503 error has disappeared. If it has, you’ve successfully resolved the issue. If not, continue to the next step in the process.

1. Temporarily Deactivate WordPress Plugins

One of the most common causes of the 503 error in WordPress is plugin compatibility issues. To determine if this is the case, you need to disable all of your website’s plugins.

Since the 503 error prevents you from accessing the WordPress admin dashboard, you’ll need to perform this step using an FTP client. If you don’t have one installed, we recommend using FileZilla.

Once your FTP client is ready, connect to your website through it and navigate to your WordPress root folder. If you can’t find it, it’s usually called public_html, html, public, www, or your website’s name. The general path is /home/wwwroot/http://www.yourdomain.com/wp-content, as shown below:

WordPress Plugin FTP Directory

Open that folder and navigate to the wp-content directory. Inside, you’ll see a folder called plugins, which contains individual subdirectories for each plugin installed on your site (active and inactive).

What you need to do now is right-click on the plugins folder and rename it to something else. We recommend using plugins.old or plugins.deactivated for easy identification later.

WordPress plugins Folder Renamed

WordPress will now be unable to find any plugins. When this happens, it automatically disables them.

Now, try accessing your WordPress dashboard. If the 503 error is gone, then you can assume that one of the plugins is the culprit. All you have to do is identify the problematic plugin.

Return to the wp-content directory and rename the original plugins folder correctly. Then, you need to disable each plugin one by one until you find the culprit.

To do this, open the wp-content/plugins directory. Inside, you’ll find a folder for each plugin. The process you need to follow is roughly the same as the previous steps:

• Start with the first folder and rename it to anything you like.
• Check your website to see if the error has disappeared.
• If not, restore the plugin folder from the previous step to its original name.
• Go to the next plugin in the list and repeat the above steps.
• If you have many plugins, this process may take a while, but it is crucial to check each plugin in turn. If you identify the plugin causing the error at any point, you can uninstall it or replace it with another tool.

If you have completed these steps without finding a solution, you can proceed to the next troubleshooting step.

2. Deactivate Your WordPress Theme

Now that you’ve ruled out plugins as the cause of the 503 error, it’s time to do the same for your currently active WordPress theme. Your theme may also be causing compatibility issues.

Unfortunately, the process is different from the above. If you simply rename the theme folder, WordPress will not revert to the default theme and will eventually display errors such as “Theme directory” or “Theme name does not exist”. Or, if you try to rename the entire themes directory folder, you will eventually see “Error: The theme directory is either empty or does not exist. Please check your installation.”

Theme Directory Does Not Exist Error Message

Therefore, you need to access your WordPress database by logging into phpMyAdmin.

Click on the “wp_options” table, then click on the “Search” tab. You need to search for template under “option_name”.

Database wp_options Table

Under the “option_value” column, you will see the current name of the theme. Change it to one of the default themes, such as “twentynineteen”.

wp_options Theme Name

Check your website again to see if the error has been fixed. If it has, it means that there is a problem with your WordPress theme, and you may want to try reinstalling it or restoring it to a recent backup.

3. Temporarily Disable Your CDN (Content Delivery Network)

The process for this may vary depending on the CDN you’re using. Cloudflare is known to cause 503 errors. If you can’t find an option to pause, check your service’s knowledge base, which usually contains detailed instructions.

If you don’t use a CDN or find that pausing your service doesn’t help with your problem, then we need to try other methods. Remember to re-enable your CDN before continuing.

4. Limit WordPress’s ‘Heartbeat’ API

WordPress Heartbeat is an API built into WordPress that the platform uses to autosave content, display plugin notifications, remind you that others are working on the post you’re trying to access, and more.

Like a regular heartbeat, the API works in the background at a high frequency, so it doesn’t miss anything. As you can imagine, this API consumes server resources. Usually, this is not a problem, but in some cases, if your server cannot handle the load, it may cause a 503 error.

The quickest way to determine if the Heartbeat API is at the heart of the problem is to temporarily disable it. To do this, connect to your WordPress website via FTP again, then open the current theme folder and look for the functions.php file in the following location:

WordPress Theme’s functions.php File

Right-click on the file and select the “View/Edit” option, which will open it with a local text editor. Once opened, you need to add the following code snippet:


add_action( 'init', 'stop_heartbeat', 1 );
function stop_heartbeat() {
wp_deregister_script('heartbeat');
}


These three lines of code tell WordPress to disable the Heartbeat API. Save the changes to the functions.php file, close it, and try accessing your website again.

If the 503 error disappears, then this API is the problem. However, completely disabling it will make many useful features of WordPress unavailable. Instead, we recommend that you reduce the Heartbeat frequency of WordPress to avoid causing problems.

The easiest way to do this is to install the Heartbeat Control plugin. Enable the plugin and navigate to “Settings” > “Heartbeat Control“. Find the “Modify Heartbeat” option and reduce the frequency as much as possible:

Heartbeat Control Plugin Frequency Settings

Save the changes to your settings and return to the functions.php file. To make the above changes take effect, you need to remove the code you added to the functions.php file earlier and save the changes to the file.

At this stage, if the Heartbeat API is the problem, you should have solved the 503 error. If not, then continue to try different methods.

5. Increase Server Resources

If all the fixes so far have failed to resolve the 503 error, then the problem is likely due to a lack of server resources. That is, you need to upgrade your server to see if it solves the problem. If you are using cheap WordPress hosting, they often limit resources, causing 503 errors.

However, upgrading your server is a significant decision. A smart move is to first contact your server provider and discuss the 503 error with them, as well as the steps you have tried to resolve it so far. The support team should be able to help you troubleshoot the problem and advise you on whether you need to upgrade your server.

6. Check Logs and Enable WP_DEBUG

You should also make use of error logs. If your website server is built using LNMP, you can quickly find the website access error log through the website server’s /home/wwwlogs path (usually named nginx_error.log or error.log). This can help you quickly narrow down the problem, especially if it is caused by a plugin on your website.

Check for 503 Errors in the Error Log

If your host does not have a logging tool, you can also add the following code to the wp-config.php file to enable logging:


define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );


The debug log is usually located in the /wp-content directory. Inside it, look for a file named debug.log and open it.

Some server providers may have a dedicated folder called “logs”.

WordPress Error Log Folder (SFTP)

Viewing the debug log may be daunting for many webmasters, but it is not as difficult to read as you might think. In short, the log contains every error that has popped up on your website in chronological order. It shows the file that caused each error and the specific lines of code involved.

Note: You will not find a direct reference to the 503 error in the log. Even so, if all other methods have failed, it can point you in the right direction by showing you the files that are causing the problem. That way, you’ll know where to focus next. As we mentioned in the previous step, if you need further assistance in resolving this error, now is the time to contact your server provider and have them assist in resolving the problem. Or, find a friend who understands server operations and maintenance to help.

You can also check the log files in Apache and Nginx, which are usually located here:

• Apache: /var/log/apache2/error.log
• Nginx: /var/log/nginx/error.log

If the 503 error is caused by a fatal PHP error, you can also try enabling PHP error reporting. Just add the following code to the file where the error occurred. You can usually narrow down the file in the console tab of Google Chrome DevTools.


ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);


You may also need to modify the php.ini file with the following:


display_errors = on


Key Takeaways

Generally, the 503 error is only displayed when you put your website into maintenance mode. However, if that’s not the reason, then you’ll have to roll up your sleeves and troubleshoot.

To understand the root cause of the 503 error, you need to follow these steps to fix it:

• Temporarily deactivate WordPress plugins.
• Deactivate the WordPress theme you are using.
• Disable your website’s CDN service.
• Limit WordPress’s Heartbeat API.
• Increase server resources.
• Check logs and enable WP_DEBUG.

Have you ever encountered a 503 error in WordPress? Share your experiences with us in the comments below! For more interpretations of HTTP status codes, you can refer to the article “Common HTTP Status Code List and Corresponding Meanings”.

via How to Fix the 503 Service Unavailable Error in WordPress – 闪电博

FAQ

Q: What does a 503 error mean?

A: A 503 error indicates that the server is temporarily unavailable, usually due to being busy or under maintenance.

Q: How can I fix a 503 error on my WordPress site?

A: You can try the following steps: deactivate plugins, switch to a default theme, disable your CDN, limit the Heartbeat API, increase server resources, and check your server logs.

Q: Can plugins cause a 503 error?

A: Yes, plugin compatibility issues are a common cause of 503 errors in WordPress.