What Is 'HTTP Error 500 – Internal Server Error' and How to Fix It?

What does “HTTP 500 Internal Server Error” mean?

The “HTTP 500 Internal Server Error” is a general error message indicating that something has gone wrong on the server, but the server cannot specify the exact problem. Unlike client-side errors (like 404 Not Found), a 500 error means that the server encountered an unexpected issue that prevents it from fulfilling the request. This error can affect a single webpage or the entire website, making it crucial to diagnose and resolve it promptly.

How HTTP Status Codes Work

HTTP status codes are issued by the server in response to client requests. They are categorized as:

• 1xx (Informational): These codes indicate that the server has received the request and is continuing to process it.
  • 100 Continue: The server has received the initial part of the request and the client should continue sending the rest.
  • 101 Switching Protocols: The server acknowledges a request to switch protocols.
  • 103 Early Hints: Used to return some headers before the final response.
  Example: HTTP/1.1 100 Continue
• 2xx (Success): These codes indicate that the request was successfully received, understood, and accepted.
  • 200 OK: The request was successful, and the response body contains the requested data.
  • 201 Created: A new resource has been created as a result of the request.
  • 204 No Content: The server successfully processed the request, but there is no content to return.
  Example: HTTP/1.1 200 OK Content-Type: application/json { "message": "Success", "data": {...} }
• 3xx (Redirection): These codes indicate that further action is needed to complete the request.
  • 301 Moved Permanently: The resource has been permanently moved to a new URL.
  • 302 Found (Temporary Redirect): The resource is temporarily moved to a different URL.
  • 304 Not Modified: The requested resource has not been modified since the last request.
  Example: HTTP/1.1 301 Moved Permanently Location: https://newdomain.com/newpage.html
• 4xx (Client Errors): These codes indicate an error caused by the client.
  • 400 Bad Request: The server cannot process the request due to client error.
  • 401 Unauthorized: The request requires authentication.
  • 403 Forbidden: The client does not have permission to access the requested resource.
  • 404 Not Found: The requested resource could not be found on the server.
  Example: HTTP/1.1 404 Not Found Content-Type: text/html <h1>404 - Page Not Found</h1>
• 5xx (Server Errors): These codes indicate an error on the server side.
  • 500 Internal Server Error: A generic error message when the server encounters an unexpected condition.
  • 501 Not Implemented: The server does not recognize the request method.
  • 502 Bad Gateway: The server received an invalid response from an upstream server.
  • 503 Service Unavailable: The server is temporarily overloaded or under maintenance.
  • 504 Gateway Timeout: The server did not receive a timely response from another server.
  Example: HTTP/1.1 500 Internal Server Error Content-Type: text/html <h1>500 - Internal Server Error</h1>

The 500 Internal Server Error falls under the 5xx category, indicating that the issue originates from the server.

What are the common problems that can cause HTTP 500 Internal Server Error?

Several issues can trigger a 500 Internal Server Error, including:

1. Faulty or Misconfigured .htaccess File – Incorrect syntax in the .htaccess file can break the server’s functionality.
2. PHP Errors – Issues such as syntax errors, memory limit exhaustion, or fatal script failures can trigger this error.
3. Insufficient File Permissions – Files and directories may have incorrect permission settings, preventing proper execution.
4. Corrupted or Incompatible Plugins/Themes – In CMS platforms like WordPress, a faulty plugin or theme may cause conflicts.
5. Exhausted PHP Memory Limit – When a script consumes too much memory, the server may crash, leading to a 500 error.
6. Database Connection Issues – If the database server is down or misconfigured, the website may return a 500 error.
7. Server Overload or Misconfigurations – High traffic or poorly optimized server configurations can cause unexpected crashes.
8. Corrupt Core Files – A corrupted WordPress core file or missing essential files can lead to a 500 error.
9. Incorrect File Ownership – If files are owned by an incorrect user or group, the server may fail to execute them properly.
10. Timeout Issues – Long-running scripts or unoptimized queries may cause a server timeout.

How to Fix the “500 Internal Server” Error?

1. Check Web Server Logs

eg. LiteSpeed’s Error Log
tail -f /usr/local/lsws/logs/error.log

This will show real-time errors that can help diagnose the issue.

2. Check and Edit the .htaccess File

• Access the root directory via FTP or file manager.
• Rename the .htaccess file (e.g., .htaccess_backup) and reload the website.
• If the site works, regenerate the .htaccess file via the CMS or manually.

Command to Rename .htaccess via SSH:

mv .htaccess .htaccess_backup

3. Increase PHP Memory Limit

• Modify the php.ini file to increase the memory limit.
• Add memory_limit = 512M; to your php.ini file.

Command to Edit php.ini via SSH:

echo "memory_limit = 512M" >> /etc/php.ini

Restart the Web Server to Apply Changes:

Note: only restarting the Webserver can also solve the issues *

Apache:

systemctl restart apache2

Nginx:

systemctl restart nginx

LiteSpeed:

systemctl restart lsws

3. Disable Faulty Plugins (For WordPress Sites)

mv wp-content/plugins/plugin-name wp-content/plugins/plugin-name-disabledThis will disable the plugin without breaking the site.

Case Study: Fixing a 500 Error in a High-Traffic LiteSpeed Website

A client running a WooCommerce store faced frequent 500 errors. By checking LiteSpeed logs, we found excessive memory usage in PHP scripts. Increasing the memory_limit and optimizing database queries resolved the issue, restoring site performance.

By following these troubleshooting steps, you can effectively resolve 500 Internal Server Errors on LiteSpeed and other web servers.

Summary

The “HTTP 500 Internal Server Error” is a complex issue requiring systematic troubleshooting. From checking .htaccess files and PHP configurations to debugging database connections and plugins, following structured steps can help diagnose and resolve the issue effectively. By implementing best practices and preventive measures, website owners can minimize the risk of encountering this error in the future.