How to Diagnose Website Errors (500/404/403 Errors)

1. How to Diagnose Website Errors (500/404/403 Errors)

500 Internal Server Error

What’s happening? The server encountered an unexpected issue (e.g., code errors, plugin conflicts).

How to Fix:

1. Check Server Logs
   • For Apache: Open terminal and run:

     tail -n 20 /var/log/apache2/error.log

   • For Nginx: Open terminal and run:

     tail -n 20 /var/log/nginx/error.log

2. Fix PHP Syntax Errors

   Example broken code:

   Fixed code:

3. Increase PHP Memory Limit

   Add to wp-config.php:

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

404 Not Found Error

What’s happening? The page/resource you’re trying to access doesn’t exist.

How to Fix:

1. Redirect Broken Links

   Add to .htaccess:

   Redirect 301 /old-page /new-page

2. Create a Custom 404 Page

403 Forbidden Error

What’s happening? Access denied (e.g., incorrect file permissions).

How to Fix:

1. Fix File Permissions

   chmod 644 filename.php  // For files
   chmod 755 directory/    // For folders

2. Disable Directory Listing

   Add to .htaccess:

   Options -Indexes

2. Steps to Debug "White Screen of Death" (WSOD)

How to Fix:

1. Enable Debugging

   Add to wp-config.php:

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

2. Increase PHP Memory Limit

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

3. Disable Plugins/Themes

   Rename the plugins folder via FTP (e.g., plugins_deactivated).

3. Resolving Slow Website Performance

Server-Side Fixes

1. Enable Caching

   
     ExpiresActive On
     ExpiresByType image/jpg "access 1 year"
     ExpiresByType text/css "access 1 month"
   

Client-Side Fixes

1. Optimize Images

   Use TinyPNG to compress images.

4. Fixing Broken Links

How to Fix:

1. Redirect Broken Links

   Redirect 301 /broken-link https://example.com/new-link

5. Browser Developer Tools

How to Use:

1. Open DevTools

   Windows: F12 or Ctrl + Shift + I
   Mac: Cmd + Option + I

2. Debug JavaScript Errors

   Go to the Console tab to view errors.