What is 500 Internal Server Error? What causes a WordPress 500 error, and how do you fix it?

How do you diagnose the problem using server error logs and WP_DEBUG_LOG?

The cause of 500 Internal Server Error can be read from the line in the server error log or WordPress debug.log. The error page gives visitors no details, but the server often records the file and line where the error occurred. Starting diagnosis here produces results faster than randomly disabling plugins.

The error log in the hosting panel

Hosting panels usually offer an error log section; on some servers, PHP errors are also written to a file named error_log in the folder where the error occurred. Look for expressions such as “PHP Fatal error,” “Allowed memory size exhausted,” or “Invalid command.” If the file path contains a folder under wp-content/plugins, the responsible plugin can often be identified there.

WP_DEBUG and WP_DEBUG_LOG

According to WordPress’s Debugging documentation, WP_DEBUG is disabled by default; enabling WP_DEBUG_LOG writes errors to wp-content/debug.log. Setting WP_DEBUG_DISPLAY to false records errors only in the file without showing them to visitors. The lines added to wp-config.php are as follows:

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

The same documentation discourages using debugging tools on live sites; they are intended for local and staging installations. If enabled briefly to diagnose a live site, disable the settings and delete debug.log after finding the problem. Reading the log and the recovery mode email in the WordPress critical error guide are explained step by step.

How do you regenerate a corrupted .htaccess file?

A clean .htaccess file is generated by renaming the corrupted file and saving Permalinks settings again. WordPress documentation presents this method as the first step for Internal Server Error. Perform the operation through FTP or the hosting panel’s file manager:

1. Find .htaccess in the site’s root directory, in the same folder as wp-config.php; because its name begins with a dot, enable “show hidden files.”
2. Rename the file to .htaccess_old; do not delete it, because it may contain redirect or security rules.
3. Try the site again. If it opens, the problem is in .htaccess.
4. In the administration panel, open Settings › Permalinks and click “Save Changes” without changing anything; WordPress writes a new .htaccess file.
5. Check custom rules in the old file, such as 301 redirects, line by line and add them back to the new file.

Servers using Nginx do not read .htaccess; their rewrite rules are in server configuration, so this step has no effect. If the file is not regenerated, check the folder’s write permissions.

How do you test plugin and theme conflicts without accessing the panel?

If the panel is inaccessible, disable plugins collectively by renaming wp-content/plugins. WordPress does not load plugins whose folders it cannot find; settings remain because files are not deleted. This method also appears in WordPress’s common errors documentation.

The sequence is as follows: rename plugins to plugins_old and test the site. If it opens, restore the folder name and activate plugins individually through the panel; the plugin bringing back 500 is responsible. If a particular plugin is suspected, rename only that plugin’s folder.

If the theme is suspected, rename the active theme folder under wp-content/themes and WordPress falls back to an installed default theme. If nothing works, the documentation also recommends uploading wp-admin and wp-includes again from a clean WordPress package. These folders contain only core files; wp-content and wp-config.php are left untouched.

How do you check PHP memory limits, the PHP version, and file permissions?

If the log says “Allowed memory size exhausted,” examine the PHP memory limit; for “syntax error” or undefined-function errors, examine the PHP version; for “Permission denied,” examine file permissions. These three causes explain most 500 errors persisting after plugins are disabled.

Increasing memory with WP_MEMORY_LIMIT

According to WordPress’s wp-config.php documentation, WordPress attempts to raise PHP memory to 40 MB on a single site and 64 MB on multisite. For more, add a definition to wp-config.php before the wp-settings.php line, such as define( 'WP_MEMORY_LIMIT', '96M' ); WP_MAX_MEMORY_LIMIT can also be defined separately for administration operations. The documentation notes that some hosting companies do not permit this increase and should be contacted in that case.

PHP version compatibility

WordPress’s Server requirements page recommends PHP 8.3 or later and states that older versions such as PHP 7.4 have reached the end of official support. If the error began immediately after a PHP version change, temporarily return to the previous version through the hosting panel, identify and update the incompatible plugin, then switch back to the current version.

File permissions

WordPress’s File permissions documentation specifies 755 or 750 for folders, 644 or 640 for files, and 440 or 400 for wp-config.php. The same documentation emphasizes the security risk of 777 and states that correct values can vary between servers. Some servers refuse to execute a PHP file with overly permissive write access for security reasons and return 500.

Hosting resource limits

Shared hosting plans have CPU, memory, and simultaneous-process limits for each account; when exceeded, the server terminates the request and may return 500 or 503. If the error appears only during busy hours, bulk emailing, or backups, examine resource usage reports in the hosting panel. If it keeps recurring, consider a plan upgrade or more suitable infrastructure; the hosting package Onur Freelance opens in the business’s name costs 2,000 TL annually, and details are on the hosting prices page.

What is the difference between 500, 502, 503, and 504 errors?

500 Internal Server Error is a general server error; 502 and 504 describe communication problems between an intermediary server and an upstream server, while 503 indicates temporary inability to serve requests. Based on RFC 9110 definitions, the table below shows the differences between the four codes:

On sites using a CDN such as Cloudflare, separately check whether the error page comes from the CDN or origin server. If errors appear intermittently alongside slowness, WordPress performance checks also become relevant.

How does a 500 error affect SEO and Google rankings?

A brief 500 Internal Server Error generally does not permanently affect rankings, but prolonged 5xx errors slow crawling and may cause pages to leave the index. Google Search Central’s HTTP status codes and network errors documentation states that 5xx and 429 errors cause Google crawlers to temporarily slow crawling. According to the same documentation, Google’s indexing system removes URLs that persistently return server errors from the index.

The documentation gives no specific duration after which Google removes a page; resolving the error as quickly as possible is the safest approach. Follow these steps after repair:

• Check server error (5xx) records in Search Console’s Page indexing report.
• Retest important pages with URL Inspection.
• If scheduled maintenance is required, take the site offline using 503 to indicate a temporary condition rather than 500.
• Monitor whether error records decrease over the next few days after correction.

Random attempts or systematic diagnosis? Common mistakes

The most time is lost with 500 Internal Server Error through successive attempts without checking the log. Common practice involves deleting plugins, adding random code snippets, or rebuilding the site; a systematic approach first takes a backup, reads the log, and makes one change at a time. Common mistakes and their correct alternatives are as follows:

• Deleting a plugin through the panel or FTP: Deletion removes settings for some plugins; the correct method is renaming the folder.
• Deleting .htaccess: Its redirect and security rules are lost; rename the file and preserve its contents.
• Raising the memory limit to excessively high values: The faulty plugin causing the problem is concealed, and the issue returns with the next operation.
• Setting file permissions to 777: The error may temporarily disappear, but the site becomes vulnerable to attack.
• Displaying errors on the live site: Leaving WP_DEBUG_DISPLAY enabled exposes file paths to visitors.
• Intervening without a backup: Every attempt takes the point you can return to a little farther away.

In our repair process, files and the database are backed up before every intervention, every change is recorded, and the homepage, panel, contact form, and any checkout step are tested separately after the error disappears. If unfamiliar files or new administrator accounts appear, 500 may indicate a security breach rather than incompatibility.

When should you consult a specialist for 500 Internal Server Error?

Specialist support saves time if 500 Internal Server Error persists despite regenerating .htaccess, disabling plugins, and checking memory. Diagnosis should be systematic especially when there is no current backup, e-commerce orders have stopped, the error log is inaccessible, or the error appears only at particular hours.

For one-time failures, the WordPress troubleshooting service reads the log, identifies the cause, and gets the site live again. If regular monitoring of updates, backups, and PHP version transitions is wanted, the annual WordPress maintenance and updates service makes this an ongoing process. WordPress maintenance costs 500–2,000 TL per month depending on the site’s size and scope.