Troubleshooting Critical Errors and 500 Issues with Kadence Theme and Plugins

Encountering a critical error or a 500 Internal Server Error on your WordPress site can be alarming, especially when it seems linked to a specific theme like Kadence. Based on common community reports, this guide will help you understand why these errors occur and walk you through the most effective troubleshooting steps to resolve them.

Common Symptoms and Error Messages

Users often report issues such as:

• A white screen with the message "There has been a critical error on your website."
• HTTP 500 errors in server logs, particularly related to wp-json/wp/v2/kadence_navigation.
• Fatal PHP errors mentioning files within /wp-content/themes/kadence/ or /wp-content/plugins/kadence-blocks/.
• Problems that only affect logged-out users or users with specific roles (like Editors), while the site works fine for administrators.
• Errors that appear after a website restore, update, or when using specific plugins like LearnPress.

Why Do These Errors Happen?

These errors are typically not caused by a single issue but often stem from conflicts or compatibility problems. The most frequent root causes include:

1. Plugin or Theme Conflicts: Another plugin, or sometimes a specific function within the Kadence theme itself, may be incompatible. This is a very common cause, especially with page builders, LMS plugins like LearnPress, or caching plugins.
2. Outdated Software: Running an old version of the Kadence theme, Kadence Blocks plugin, WordPress, or PHP can lead to unexpected errors and security vulnerabilities.
3. Corrupted Files: A incomplete update, failed restore, or file corruption can break core functionality.
4. Insufficient Server Resources: A lack of PHP memory (PHP memory limit) or strict server security rules (mod_security) can trigger 500 errors.

Step-by-Step Troubleshooting Guide

1. Enable Debugging to Get Detailed Error Logs

The absolute first step is to turn on WordPress debugging to get a specific error message instead of a generic "critical error." This message is your best clue.

1. Access your website's files using an FTP client or your web host's file manager.
2. Locate and edit the wp-config.php file in your site's root directory.
3. Find the line that says define('WP_DEBUG', false); and replace it with the following code:

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

4. Save the file and upload it back to your server.
5. Now, reproduce the error by visiting the page where it occurs.
6. A new file called debug.log will be created in your /wp-content/ directory. Check this file for the specific error message.

2. Perform a Conflict Test

This is the most reliable way to identify if another plugin is causing the problem.

1. Deactivate All Plugins: Temporarily deactivate every plugin on your site except those from Kadence (e.g., Kadence Blocks).
2. Check if the Error is Gone: If the error resolves, you know a plugin conflict is the cause.
3. Reactivate Plugins One by One: Reactivate your plugins one at a time, checking your site after each activation. When the error reappears, you have found the conflicting plugin.

3. Check for Updates

Ensure everything is up to date. Outdated software is a prime source of bugs.

• Update the Kadence Theme
• Update the Kadence Blocks plugin
• Update WordPress core
• Update all other plugins
• Contact your web host to ensure you are using a modern, supported version of PHP (e.g., PHP 8.1 or 8.2).

4. Switch to a Default Theme (Temporarily)

If the conflict test didn't pinpoint a plugin, temporarily switch your theme to a default WordPress theme like Twenty Twenty-Four. If the error disappears while using the default theme, it confirms the issue is specifically with the Kadence theme or its configuration. You can then switch back to Kadence and focus your troubleshooting there.

5. Increase PHP Memory Limit

A low memory limit can cause 500 errors. Try increasing it by adding this line to your wp-config.php file:

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

What to Do with the Information You Find

• If you find a conflicting plugin: You can keep it deactivated and look for an alternative, check the plugin's support forums for a known compatibility issue, or wait for an update from the plugin developer.
• If you get a specific error message: Searching for the exact error message online often leads to community forums or articles with specific solutions.
• If the error is with the Kadence theme itself: Re-installing the theme can often fix issues caused by corrupted files. Download a fresh copy from your source and upload it via FTP, replacing the existing files.

By methodically working through these steps, you can almost always identify and resolve the underlying cause of critical errors related to the Kadence theme, restoring your site's functionality.