How to Fix WordPress Customizer Not Working

The WordPress Customizer is such a powerful assistant in building a unique and appealing website.

The advantage of the WordPress Customizer is it allows us to easily and drastically make changes to the appearance of our site with just a few clicks in the options panel and even preview these changes in real-time.

However, this awesome assistant sometimes suddenly shuts down for some unknown reason. Common symptoms are the preview stops loading or the settings remain unsaved.

So how to fix the WordPress Customizer not working?

In this article, we will be spelling out why your WordPress customizer stops working as well as suggesting some workable solutions.

Why WordPress Customizer Not Working and How to Fix

There could be a few reasons why your WordPress Customizer doesn’t work. It could be due to the plugin conflict (conflict between 2 plugins), plugin script error in your preview, or the 500 – Internal Server Error.

Another reason could be your server not having enough memory to run all of the software installed, which includes WordPress, themes, and plugins. Having different WordPress addresses (URL) and site addresses (URL) also causes the Customizer not to work properly.

Every culprit behind the faulty Customizer will be identified and listed below, along with the effective answer.

However, before we get started, make sure that you update your WordPress, active themes, and plugins to the latest version, as well as backing up your website. Whenever you’re done preparing, we’re good to go!

Plugin Conflicts

The most common reason for the defective Customizer is a plugin conflict. It can cause the Customizer Preview to stop loading or part of it to stop working properly. Even if you don’t make any changes to your site or haven’t installed any new plugins, this problem is still caused by the previously installed plugin, for example, the plugin leftovers on your website.

How to fix:

In case you don’t know which plugin causes the conflict, then just disable all plugins and see if it solves the Customizer issue.

  • If you have a cache plugin or server cache, you need to delete its cache content and disable it.
  • Deactivate all of your plugins at once.
  • Clear your browser history and visit Appearance > Customize to see if it works. If it works properly, there is a high chance that your server is not having enough memory.
  • Re-activate plugins, one by one.
  • After each activation, visit Appearance > Customize to see if it works. If the problem reoccurs, then you’ll know which plugin needs more attention.

When you’ve found the plugin that breaks your Customizer, you can:

  • Keep that plugin activated and deactivate all other plugins.
  • Visit Appearance > Customize to see if it works.
  • If it works, it’s probably not the plugin conflict but your server is not having enough resources.
  • If it doesn’t, then you’ve found a plugin causing conflict.

Different WordPress Address (URL) and Site Address (URL)

Different WordPress addresses (URL) and site addresses (URL) will lead to the preview not loading. To prevent this from happening, your WordPress address and site address need to be identical.

How to fix:

  • First, log in to your WordPress Dashboard.
  • Go to “Setting,” choose “General.”
  • Edit the “WordPress Address” and “Site Address” options.Edit WordPress address and site address
  • Click on the “Save Changes” button to save your settings. You can now visit Appearance > Customize to see whether it works properly.

    Note: Different URLs are also the reason behind the Too Many Redirects error in WordPress.

Missing or Invalid Menu Items

Another culprit causing the WordPress Customizer to stop working is the missing or invalid menu items. If you deleted any pages or posts added to your WordPress menu, there could be some blocking issues.

How to fix:

  • Head over to Appearance > Menu to check if there’re any invalid items.
  • Locate the invalid menu items (usually marked in red) and remove them.

Invalid menu items

500 – Internal Server Error

When you try to save the Customizer settings and this error shows up, then you might have to consider these major causes:

  • The server is using an old version of PHP.
  • The server is running out of resources.
  • PHP has an error processing the request.

How to fix:

The Server is Using an Old Version of PHP

If your server has an outdated version of PHP, the WordPress Customizer won’t load and display an error like this: “Parse error: syntax error, unexpected T_FUNCTION in…”

Contact your hosting company to ask them which version of PHP your website is using. If it’s lower than 5.4, tell them to update it to the latest version. Your PHP version should be at least 5.6 or better yet, 7.0.

The Server is Running Out of Resources

In this case, you need to contact your hosting company and ask them if the server is running out of resources. If yes, ask them to allocate more memory to your PHP. Your host company will be able to fix this by updating the PHP configuration.

PHP Has an Error Processing the Request

You need to check the PHP error logs to see if there’re any errors. If you aren’t able to interpret the data, contact your hosting provider and they will be able to check the PHP error logs, as well as determining the root cause of the error.

The Final Solution on How to Fix WordPress Customizer Not Working

In case you’ve tried examining all of the possibilities above but the WordPress Customizer is still not working, and you have no idea why the issue arises, then you should try out this way.

Add the following code snippet to the file functions.php of your child theme, and see if it helps to solve the issue.

remove_action('shutdown', 'wp_ob_end_flush_all', 1);

Sweet Bonus: Customizing Email Templates Using YayMail

In some cases, even when you deactivated plugins, their configs and settings still remain in the database. Especially when your website has switched among a couple of themes and plugins that use the WordPress customizer, it can act weird due to some conflicts.
WordPress Customizer's multiple customizer options

In order to prevent some Woo customizer plugins from being built into the WordPress Customizer, you can use alternative plugins that provide the functionality you need.

For instance, instead of using the customizer for WooCommerce emails, you can use a dedicated email builder like YayMail.

It’s a drag and drop email builder framework that helps you design and reorder every email block. YayMail overcomes the limitations of WooCommerce default email settings and the fixed page customizer. Just like using the Elementor page builder, it makes designing email templates a breeze.

You can download the YayMail free version today and enjoy customizing by Drag and Drop.


If you’re struggling to diagnose your WordPress Customizer problem, as well as figuring out how to fix it, this article hits the spot!

We’ve pointed out several possible culprits behind your faulty Customizer and provided you with detailed and practical solutions.

By following our guide, you’ll gain considerable knowledge about how to deal with your WordPress Customizer when it stops working. Plus, you can use YayMail to extend the WooCommerce default email settings and the fixed page customizer.

Have you ever faced the WordPress Customizer that stopped working? And how did you fix it? Let us know by leaving comments below!