Customizer Preview is not working ( Appearance -> Customize )

You may have login to your WordPress dashboard -> Appearance -> Customize and found that it's not loading or some settings are not working properly.

There could be a few reasons why your Appearance -> Customize does not work.

  1. It could be due to plugin conflict, or plugin outputting conflicting script in your preview.
  2. It could be your server not having enough memory to run all the software installed. Which includes WordPress, Customizr Pro Theme and your large collection of plugins.
  3. Or maybe your computer does not have enough processing power to run it.
  4. You are having a different WordPress Address (URL) and Site Address (URL)

Troubleshooting Steps

WordPress Address (URL) and Site Address (URL)

  1. Login to your WordPress dashboard
  2. Go to Settings -> General
  3. Your WordPress Address (URL) and Site Address (URL) has to be identical.
    The preview will not load if you are having a different URL

Server Memory Issue

  1. Activate Customizr Pro Theme, then deactivate all your plugins.
  2. With all your plugins remain deactivated, visit Appearance -> Customize and see if it works properly. 
  3. If it works properly, there is a high chance that your server is not having enough memory to run. 
  4. To confirm this issue.
    • Randomly active back a few "large" plugins and check if your customizer is working properly. 
    • If yes, this confirms that you are having a memory issue. You will have to contact your web hosting company to increase your resources, or deactivate a few not important plugin

Plugin Conflict or Error 

A plugin conflict or code error can cause Customizer Preview to stop loading or part of it to stop working properly.

  1. If you have a cache plugin or server cache. You need to purge it's cache contents and disable it.
  2. De-active all your plugins.
  3. Re-activate back one plugin at a time. 
  4. Clear your browser history and visit your Appearance -> Customize to see if it works.
  5. If you have found a plugin that breaks your Appearance -> Customize.
    • You can double check by activating only this plugin and deactivate all other plugins.
    • Visit Appearance -> Customize and see if it works.
    • If it works, then it's not a plugin conflict, it's your server not having enough resources.
    • If it does not work, then you have found the plugin that's causing conflict.

Computer Hardware

Some notebook computers may not have enough processing power to run your browser while in Customizer Preview.

  1. Try to find another desktop computer which is almost new. 
  2. Login to your WordPress dashboard, Go to Appearance -> Customize are see if it works properly. 
  3. If it works, then the computer that you are using does not have enough processing power to run web browser in customize preview. You will have to use a more powerful computer.
  4. Switching to a stable and less demanding web browser such as Firefox, may work on a notebook computer.

Written by Denzel Chia