How to Fix 500 Internal Server Error in PHP: Complete Troubleshooting

Key highlights

• Learn how to identify the root causes of PHP 500 internal server errors and pinpoint the exact issue affecting your website.
• Understand the step-by-step troubleshooting process to resolve server errors quickly and restore your site’s functionality.
• Discover common PHP configuration mistakes that trigger 500 errors and how to avoid them through proper setup and maintenance.
• Explore practical debugging techniques using error logs, PHP settings and diagnostic tools to trace error sources effectively.
• Know the essential preventive measures and best practices to minimize future 500 errors and maintain optimal server performance.

Nothing is more frustrating than seeing your website display a dreaded HTTP 500 internal server error instead of your carefully crafted content. If you’re wondering how to fix 500 internal server error in PHP, you’re not alone—this is one of the most common issues website owners face. The good news? Most PHP 500 errors can be resolved quickly once you understand the root cause and follow the right troubleshooting steps.

In this comprehensive guide, we’ll walk you through everything you need to know about diagnosing and fixing HTTP 500 status code errors in PHP scripts. Whether you’re running a WordPress site, custom PHP application or managing multiple websites, these proven solutions will help you get your site back online quickly and prevent future occurrences.

What is an HTTP 500 status code?

An HTTP 500 status code, officially known as an “Internal Server Error,” is a generic error message indicating that something went wrong on the server side, but the server cannot specify exactly what the problem is. When it comes to PHP applications, this error typically means your PHP script encountered an issue that prevented it from executing properly.

Unlike client-side errors (400-499 status codes), a 500 error indicates the problem lies with the server or your website’s code, not with the user’s browser or internet connection. This makes it particularly important to address quickly, as it affects all visitors to your site.

500 server error response

When a 500 internal server error occurs, your web server returns a generic “Internal Server Error” message to visitors instead of revealing specific technical details about what went wrong. This intentional vagueness serves as a security measure, preventing potential attackers from seeing sensitive information about your server configuration, file paths or code structure that could be exploited.

For PHP script troubleshooting, this means you cannot rely on what visitors see in their browsers. Instead, you must examine your server’s error logs and PHP logs to identify the actual cause—whether it’s a syntax error, memory limit issue, file permission problem or configuration conflict. Common symptoms users encounter include completely blank pages, the generic “Internal Server Error” message or API clients receiving basic 500 status responses. Remember, this is always a server-side issue, not a browser or user connectivity problem.

Common causes of PHP 500 internal server errors

Identifying the underlying issue is essential when learning how to fix 500 internal server error in PHP. Multiple factors can trigger this error and understanding each one helps you diagnose and resolve the problem more efficiently. Below are the most common causes you’ll encounter:

1. Syntax errors in PHP code

Even minor coding mistakes can cause major problems. Missing semicolons, unclosed brackets, mismatched parentheses or incorrect function calls will immediately trigger a 500 internal server error. A single misplaced character or typo in your PHP code can halt script execution entirely, preventing your website from loading properly.

2. File permission issues

Incorrect file permissions can prevent the web server from reading or executing your PHP scripts correctly. When permissions are too restrictive or overly permissive, they create security vulnerabilities or functionality issues. Generally, PHP files should have 644 permissions (readable and writable by owner, readable by others), while directories require 755 permissions (executable and accessible by all users).

3. Memory limit exceeded

PHP scripts have memory limits defined in your server configuration. When your script attempts to consume more memory than the allocated limit allows, the server automatically terminates the process to protect system resources. This termination results in a 500 internal server error being displayed to visitors instead of your website content.

4. Plugin or theme conflicts

Within WordPress and other content management systems, incompatible or poorly coded plugins and themes are frequent culprits behind 500 errors. These conflicts often emerge immediately after updating WordPress core, themes or plugins. When two extensions attempt to use the same resources or contain conflicting code, the resulting clash can crash your entire site.

5. Corrupted .htaccess file

The .htaccess file controls critical server configuration directives for Apache web servers. When this file becomes corrupted, contains syntax errors or includes incompatible directives, it can prevent the server from processing requests correctly. Even a small formatting mistake in your .htaccess file can generate 500 internal server errors across your entire website.

6. PHP version incompatibility

PHP continues to evolve, with newer versions deprecating outdated functions and syntax. If your code uses deprecated functions, removed features or syntax patterns no longer supported by your current PHP version, the server will be unable to execute the script. This incompatibility between your code and the PHP version running on your server commonly triggers 500 errors.

Step-by-step troubleshooting guide to fix 500 internal server error in PHP

Follow these systematic steps to diagnose and resolve your PHP 500 error:

Step 1: Check your error logs

Your server’s error logs contain detailed information about what caused the HTTP 500 status code. Most hosting providers, including those with advanced PHP configurations, provide easy access to error logs through their control panels.

Look for recent entries that correspond to when the error occurred. Common log locations include:

• /public_html/error_logsvar/log/apache2/error.log
• Your hosting control panel’s error log section

Step 2: Test your .htaccess file

Temporarily rename your .htaccess file to .htaccess-backup and check if your site loads. If it does, the .htaccess file was causing the issue.

To fix a corrupted .htaccess file:

1. Create a fresh .htaccess file with basic WordPress rules.
2. Add custom rules one by one to identify the problematic code.
3. Ensure proper syntax for all directives.

Step 3: Verify file permissions

Incorrect permissions are a common cause of 500 errors. Use your hosting control panel’s file manager or FTP client to check permissions:

• Files: 644 (rw-r–r–)
• Directories: 755 (rwxr-xr-x)
• wp-config.php: 600 (rw——-) for security

Step 4: Increase PHP memory limit

Memory exhaustion frequently causes 500 errors. Try increasing your PHP memory limit through one of these methods:

Via wp-config.php (WordPress):

Add this line before “That’s all, stop editing!”:

ini_set('memory_limit', '256M');

Via .htaccess file:

php_value memory_limit 256M

Step 5: Deactivate plugins and themes

For WordPress sites, plugin conflicts are notorious for causing 500 errors. Deactivate all plugins by renaming the plugins folder to plugins-off, then reactivate them one by one to identify the culprit.

If deactivating plugins resolves the issue, you’ve found your answer. Similarly, switch to a default theme to rule out theme-related problems.

Step 6: Check PHP version compatibility

Ensure your website’s code is compatible with your server’s PHP version. Deprecated functions in newer PHP versions commonly trigger 500 errors.

Bluehost PHP configuration solutions

If you’re hosting with Bluehost PHP configuration options, you have additional tools at your disposal:

1. Using the control panel

Access your hosting control panel and navigate to the PHP settings section. Here you can:

• Adjust PHP memory limits
• Change PHP versions
• Modify execution time limits
• Enable error reporting for debugging

2. PHP error reporting

Enable detailed error reporting to get more specific information about what’s causing your 500 error. Add these lines to your wp-config.php file:

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

3. Database connection issues

Sometimes 500 errors stem from database connectivity problems. Verify your database credentials in wp-config.php and ensure your database server is responding properly.

What is php.ini?

PHP.ini is PHP’s primary configuration file that controls how your PHP scripts run on the server. Think of it as the master control panel that sets important limits and behaviors for your website’s PHP code. When it comes to 500 errors, php.ini settings like memory_limit, max_execution_time, upload_max_filesize and error logging configurations often play a crucial role in whether your scripts run successfully or crash.

Common php.ini misconfigurations that trigger 500 errors include setting memory limits too low for your site’s needs, restrictive execution time limits that cut off complex processes or upload limits that are smaller than the files users try to upload. Adjusting these settings in php.ini is often safer than modifying your website’s code because it affects server behavior without changing your actual application logic. However, make changes carefully and test each modification individually to ensure your site remains stable and performs as expected.

Generate php.ini

Creating a custom php.ini file allows you to adjust PHP settings without modifying server-level configurations. This approach is particularly useful when standard configuration changes haven’t resolved your 500 error.

1. Access your hosting environment through your control panel’s file manager or via FTP client.
2. Navigate to your site’s root directory (typically public_html or your domain folder).
3. Create a new file named “php.ini” in this location.
4. Add your desired directives, such as:
   memory_limit = 256M

max_execution_time = 60

upload_max_filesize = 64M
5. Save the file and test your site to see if the error resolves.
6. Verify the settings are active by creating a temporary PHP file with and checking if your values appear.

Always modify one directive at a time and re-test your site after each change to isolate which specific setting resolves the issue.

Advanced troubleshooting techniques to fix 500 internal server error in PHP

1. Enable WordPress debug mode

For WordPress sites, enable debug mode to get detailed error information:

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

2. Check server resource usage

High CPU usage or bandwidth limitations can trigger 500 errors. Monitor your resource usage and consider upgrading your hosting plan if needed.

3. Review recent changes

Think about what changed recently before the error appeared:

• New plugin installations or updates
• Theme modifications
• PHP version changes
• Server configuration updates

4. PHP FastCGI

• PHP FastCGI is a communication protocol that enables web servers to process PHP scripts more efficiently by maintaining persistent connections rather than starting new processes for each request. When FastCGI encounters misconfigurations, timeout issues or resource limits, it can trigger 500 internal server errors without clear explanations.
• Check your hosting control panel to verify the active PHP version and handler settings, ensuring they match your website’s requirements and haven’t been accidentally modified during recent updates.
• Review your error logs for messages containing “FastCGI,” “handler,” or “timeout” references, which often pinpoint specific configuration problems or resource limitations causing the failures.
• If you recently changed PHP settings, upgraded versions or modified server configurations, try reverting these changes to determine if they triggered the FastCGI-related errors.
• Contact your hosting provider’s support team if these basic checks don’t resolve the issue, as FastCGI problems typically require server-level configuration adjustments beyond standard user access permissions.

Prevention best practices for HTTP 500 status code

Preventing 500 errors is better than fixing them. Follow these best practices:

1. Regular backups: Maintain current backups of your website files and database. This allows you to quickly restore a working version if issues arise.
2. Test changes in staging: Always test new plugins, themes or code changes in a staging environment before applying them to your live site.
3. Keep everything updated: Regularly update your PHP version, CMS, plugins and themes to ensure compatibility and security.
4. Monitor error logs: Regularly check your error logs to catch and address issues before they become major problems.

When to contact professional support?

While many 500 internal server errors in PHP can be resolved independently, some situations require professional assistance:

• Error logs don’t provide clear information
• The error persists after trying all troubleshooting steps
• You’re uncomfortable making server-level changes
• The error affects critical business operations

Quality hosting providers offer 24/7 support specifically for these situations, with experienced technicians who can quickly diagnose and resolve complex server issues. With Bluehost WordPress hosting, you get access to expert 24/7 support that can help you troubleshoot PHP 500 errors and resolve server issues fast, ensuring minimal downtime for your website.

Final thoughts

Learning how to fix 500 internal server error in PHP is an essential skill for anyone managing websites. By systematically checking error logs, verifying file permissions, testing plugins and themes and ensuring proper PHP configuration, you can resolve most 500 errors quickly and effectively.

Remember that prevention is key—maintain regular backups, test changes in staging environments and keep your software updated. When you encounter persistent issues, don’t hesitate to reach out to your hosting provider’s support team for assistance.

Ready to ensure your website runs smoothly without 500 errors? Bluehost offers reliable WordPress hosting with optimized PHP configurations, 24/7 expert support and 99.9% uptime guarantee to help prevent these issues from occurring in the first place.

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