A 500 Internal Server Error is one of the most common issues on WordPress websites. It can be caused by various factors, including server misconfiguration, incorrect file permissions, broken files, plugin conflicts, or PHP memory limits.

This guide outlines the key reasons behind the 500 Internal Server Error and provides solutions to fix it.

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Common Causes & Fixes for 500 Internal Server Error in WordPress

1. Web Server Misconfiguration

A misconfigured Apache or IIS web server can trigger a 500 Internal Server Error. If incorrect directives are in place, the server may fail to process requests.

Fix:

• Contact your hosting provider and ask for a web server diagnosis.
• If you have access, check the server logs to identify misconfigurations.

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2. Incorrect File & Folder Permissions

WordPress requires correct permissions for files and folders. If incorrect permissions are set, the server may deny access, causing a 500 error.

Fix:

• Ensure folders have a 755 permission setting.
• Ensure files have a 644 permission setting.
• Avoid using 777 permissions, as it can cause security vulnerabilities.

You can modify these settings via an FTP client or using the command line:

chmod 755 wp-content
chmod 644 wp-config.php

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3. Corrupted Files & PHP Errors

If WordPress files become corrupted, or if there are syntax errors in PHP files, the server may reject the request, leading to a 500 Internal Server Error.

Fix:

• Reinstall WordPress to restore default files.
• Deactivate plugins that may be causing conflicts.
• Switch to a default theme (e.g., Twenty Twenty-Four) to check for theme-related errors.

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4. Issues with the .htaccess File

The .htaccess file controls many WordPress functions, including permalinks and server configurations. If this file is corrupted, it can lead to a 500 error.

Fix:

1. Access your site via FTP and locate the .htaccess file in the root directory.
2. Rename it to something like .htaccess-backup.
3. Create a new blank .htaccess file and upload it to the server.
4. Open your WordPress Dashboard → Settings → Permalinks, and click Save Changes to regenerate the .htaccess file automatically.

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5. Conflicting Plugins

Some third-party plugins may conflict with WordPress, causing server errors.

Fix:

• Deactivate all plugins via the admin panel.
• Reactivate them one by one to identify the problematic plugin.
• If you cannot access the admin panel, rename the /wp-content/plugins/ folder using FTP to disable all plugins at once.

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6. Insufficient PHP Memory Limit

WordPress requires sufficient PHP memory to execute scripts. If the memory limit is too low, the site may encounter a 500 error.

Fix:
Increase PHP memory limits by adding the following line to wp-config.php:

define('WP_MEMORY_LIMIT', '256M');

Alternatively, modify php.ini if you have server access:

memory_limit = 256M
max_execution_time = 180
post_max_size = 64M
upload_max_filesize = 64M

If you cannot change these settings, contact your hosting provider to request an increase in memory limits.

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Final Steps

If you still experience 500 Internal Server Errors, follow these steps:
Check error logs (wp-content/debug.log or server logs) for details.
Switch to a default WordPress theme to rule out theme-related issues.
Reinstall WordPress core files while keeping the wp-content folder intact.
Contact your hosting provider for further troubleshooting if the issue persists.

By following this guide, you should be able to identify and fix the 500 Internal Server Error on your WordPress site efficiently.