Enable WordPress Debugging & Check Server Error Logs

This is your first and most critical step. A 500 error means PHP crashed, but it often leaves a trace. Enable WordPress debugging to catch any PHP warnings or notices, and more importantly, check your server's raw error logs. This will often tell you the exact file and line number causing the fatal error.

• WordPress Debugging: Via FTP/SFTP or your hosting file manager, edit wp-config.php in your WordPress root directory. Add or modify these lines:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false ); // Set to false for security on live sites

After saving, try to access your site again. If a PHP error is the cause, a debug.log file will be created in your wp-content directory, containing the error details.

• Server Error Logs: These are more robust. For Apache, look for error.log (often in /var/log/apache2/ or your hosting control panel's logs section). For Nginx, it's typically /var/log/nginx/error.log. These logs will show server-level errors, including .htaccess parsing failures or fatal PHP errors that prevent WordPress from initializing. Look for entries around the time the 500 error started.

✓ Time estimate: 5-10 minutes. Crucial for diagnosis.

Regenerate the .htaccess File

If your server logs point to an .htaccess parsing error, or if the 500 error started after you manually edited it or installed a plugin that manipulates it, this is the fix for a wordpress 500 error htaccess corrupted issue.

• Via FTP/SFTP or File Manager: Navigate to your WordPress root directory.
• Rename: Find the .htaccess file and rename it to something like .htaccess_old. This effectively deactivates it.
• Test: Try accessing your site. If the 500 error disappears, the .htaccess file was the culprit.
• Regenerate: Log into your WordPress admin dashboard (if you can). Go to Settings > Permalinks. Without making any changes, simply click Save Changes. WordPress will generate a fresh, default .htaccess file.
• If admin is also down: If you're experiencing a WordPress 500 Error on Admin Dashboard Only or the entire site is down, you'll need to manually create a new .htaccess file with the default WordPress rules:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

Upload this as .htaccess to your root directory.

✓ Time estimate: 5 minutes. Safe and effective for .htaccess issues.

Isolate functions.php Issues

If debugging (Step 1) points to an error in wp-content/themes/your-theme/functions.php, or if the 500 error started right after you modified this file, you're dealing with a wordpress 500 error functions.php problem.

• Via FTP/SFTP or File Manager: Navigate to wp-content/themes/your-active-theme/.
• Rename or Edit: Rename functions.php to functions_old.php. This will disable the file and revert your theme to its default functions (potentially breaking some theme-specific features, but allowing the site to load).
• Test: Check if your site loads. If it does, the problem is in your functions.php.
• Restore & Debug: Rename it back to functions.php. Now, open the file and systematically comment out (add // at the beginning of each line or /* ... */ for blocks) the most recent code you added, or sections identified by your debug log. Save and test after each change until the site loads. This helps you pinpoint the exact problematic line.

✓ Time estimate: 10-30 minutes, depending on code complexity. Requires careful code review.

Review SSL Configuration

A wordpress error 500 after ssl install often stems from conflicting directives or incorrect database entries.

• Check wp-config.php for Force SSL: Ensure that if you're forcing SSL, the directives are correct. Sometimes, conflicting FORCE_SSL_ADMIN or FORCE_SSL_LOGIN can cause issues if not paired with proper server configuration. Temporarily comment these out if present and test.

// define('FORCE_SSL_ADMIN', true);
// define('FORCE_SSL_LOGIN', true);

• Database siteurl and home values: Incorrect URLs in your database can lead to redirect loops and 500 errors if the server tries to force HTTPS but WordPress is still configured for HTTP. Access your database via phpMyAdmin or a similar tool. In the wp_options table, find the siteurl and home options. Ensure they both start with https://. If not, update them.
• Plugin Conflict: If you used an SSL plugin (e.g., Really Simple SSL), temporarily deactivate it by renaming its folder in wp-content/plugins/ via FTP/SFTP.

✓ Time estimate: 10-20 minutes. Requires database access.

Examine Code Affecting WordPress API Endpoints

If you're getting a wordpress api endpoint 500 error, the issue is usually with custom code interacting with the REST API. This could be in your theme's functions.php, a custom plugin, or a snippet manager.

• Check Debug Logs (from Step 1): The debug log or server error log will be paramount here. It should point to the specific file and line number within a plugin or theme that's causing the API endpoint to crash. Look for errors related to wp-json or specific custom endpoints.
• Deactivate Recent Plugins: If you recently installed or updated a plugin that interacts with the REST API, deactivate it by renaming its folder in wp-content/plugins/. Test the API endpoint again.
• Review Custom Code: Examine any recent additions to your functions.php or custom plugin files that register new API routes or modify existing ones. Look for syntax errors, incorrect callback functions, or resource-intensive operations that might be timing out.

✓ Time estimate: 15-45 minutes. Requires targeted code review.