“jQuery is not defined” WordPress Error Fix

jQuery is not defined - FireBug
Do you get “jQuery is not defined” as an error after a fresh WordPress Install? JavaScript not working at your admin panel? Don’t worry, I have the solution.

After installing two new WordPress installations with defective admin JavaScript that won’t allow me to

  • Open the menus (in the admin panel’s left side)
  • See the post editors toolbar
  • Install new plugins
  • Install new themes

I understood I was having some kind problem with the Javascript jQuery library.

I deactivated all the plugins and nothing happened. Then I started looking at the source code and googeling for quite a long time. After some serious research I discovered what caused the issue.

The Problem

While uploading the WordPress installation files onto the server I had some issues that cause some of the JavaScript files to not be uploaded / be corrupted.

The Solution

wp-includes/js
Re upload the wp-includes\js folder and overwrite whatever is in there.
That’s what fixed it for me.

I hope this helped someone, if it does, or does not – comment to help or get help.

About the author

Oren Yomtov

Hello, I’m Oren and I’m a New Ventures Consultant.

I co-founded a VC-funded startup acting as CTO, worked in Silicon Valley, served in IDF's Technological Unit, and these days I'm providing consulting services to startups and enterprises.

25 Comments

Hello, I’m Oren and I’m a New Ventures Consultant.

I co-founded a VC-funded startup acting as CTO, worked in Silicon Valley, served in IDF's Technological Unit, and these days I'm providing consulting services to startups and enterprises.

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