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Fixing Lightning Theme's Unresponsive Mobile Hamburger Menu

27 threads Sep 16, 2025 Theme → Lightning

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Many users of the Lightning theme have reported a common and frustrating issue: the mobile hamburger menu suddenly stops responding to clicks. This problem can make your site unusable on smartphones and tablets. Based on community troubleshooting, the root cause is often a JavaScript conflict, not necessarily a bug in the theme itself.

Why This Happens

The hamburger menu's functionality relies on JavaScript. An error in a script can halt all subsequent JavaScript execution on the page, effectively 'breaking' interactive elements like the menu. This error could be caused by:

  • A conflict with another plugin.
  • Custom JavaScript code (e.g., in a child theme) that contains an error.
  • A recent update to either the theme, a plugin, or WordPress core that introduced an incompatibility.

How to Troubleshoot and Fix It

Follow these steps to identify and resolve the conflict. Always start with a full site backup before making changes.

Step 1: Check for Plugin Conflicts

This is the most common cause. Temporarily deactivate all your plugins.

  1. Go to your WordPress admin dashboard.
  2. Navigate to Plugins > Installed Plugins.
  3. Select all plugins and choose Deactivate from the Bulk Actions dropdown. Click Apply.

Once all plugins are deactivated, check if the mobile menu on your site works again. If it does, you know a plugin is the culprit. Reactivate your plugins one by one, checking the menu after each activation, to identify which one is causing the problem.

Step 2: Check for JavaScript Errors

If deactivating plugins doesn't help, the next step is to look for specific error messages in your browser's console.

  1. Open your website in Chrome or Firefox.
  2. Right-click on the page and select Inspect.
  3. Click on the Console tab.
  4. Reload the page. Any red error messages that appear here are critical.

As seen in one support thread, an error like Uncaught TypeError: Cannot read properties of undefined (reading 'cycle') pointed directly to a faulty custom script (all_in_header_fixed.min.js) in a child theme. If you find an error referencing a specific .js file from your child theme, try removing or fixing that script.

Step 3: Switch to the Parent Theme

If you are using a child theme, temporarily switch to the parent Lightning theme to rule out issues caused by your child theme's functions.php or style.css files.

  1. Go to Appearance > Themes.
  2. Activate the default Lightning theme (not your child theme).
  3. Check if the menu works. If it does, the issue lies in your child theme's customization.

Step 4: Clear All Caches

If the menu works when you are logged into WordPress but not for visitors, the issue is likely related to caching. Clear any caching from your:

  • Caching plugins (e.g., W3 Total Cache, WP Super Cache).
  • Server-level cache (contact your hosting provider if unsure).
  • Browser cache (do a hard refresh with Ctrl+F5).

By systematically following these steps, you can almost always identify and fix the cause of an unresponsive mobile menu in the Lightning theme.

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