If you’re encountering the ‘jQuery is not defined’ error in WordPress, rest assured you’re not alone. This issue arises when jQuery fails to load properly, impacting the functionality of your site.

Causes of the ‘jQuery is not defined’ Error

The error is commonly found in the developer tools under the Console tab. It usually occurs due to several reasons:

1. Outdated Themes or Plugins: Compatibility issues can arise when themes or plugins are not updated after a major WordPress update.
2. Improper Script Loading: jQuery must be loaded before any other scripts that depend on it. If not, this can lead to errors.
3. JavaScript Conflicts: Scripts not loaded correctly can cause conflicts with jQuery.
4. CDN Failures: Relying on jQuery hosted on a Content Delivery Network (CDN) can fail if the CDN is unavailable.

Fixing the Error

Here are some strategies to resolve the issue:

1. Update WordPress, Themes, and Plugins

Ensure all your WordPress core, themes, and plugins are updated. Navigate to Dashboard → Updates, and update all necessary components.

2. Check if jQuery is Loaded Properly

Right-click on your WordPress site and select ‘View Page Source’ (or use Ctrl+U). Search for ‘jquery.min.js’. If you see it, jQuery is loaded properly; if not, you may need to investigate how it’s being enqueued.

3. Add a jQuery Fallback

If jQuery is loading via a CDN and it fails, you can add a fallback script to ensure it loads from your local server. It’s recommended to use a code snippet manager like WPCode to implement this safely.

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script><script>    window.jQuery || document.write('<script src="/wp-includes/js/jquery/jquery.js"></script>')</script>

4. Fix Script Loading Order

Make sure jQuery loads before any scripts that depend on it. This can usually be fixed by adjusting the code where you’re enqueuing scripts in your theme or plugins.

5. Edit wp-config.php

If previous methods fail, editing the wp-config.php could help. Access the file, and add this code to disable script concatenation:

define('CONCATENATE_SCRIPTS', false);

6. Seek Premium Support

If the error persists, consider seeking help from a premium support service that specializes in WordPress.

Bonus Resources

For further reading, look into how to troubleshoot WordPress errors, properly add JavaScripts and styles, and explore common WordPress issues that may lead to similar errors.

By following these steps, you should be able to resolve the ‘jQuery is not defined’ error and restore your site’s functionality.

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