“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

Hi, I’m Oren. I’m a technologist and entrepreneur.

I started coding at a young age, served in IDF's Technological Unit, worked in Silicon Valley, and co-founded a VC-funded startup acting as CTO.

Interested in consulting? Reach out using the contact page.

25 Comments

Hi, I’m Oren. I’m a technologist and entrepreneur.

I started coding at a young age, served in IDF's Technological Unit, worked in Silicon Valley, and co-founded a VC-funded startup acting as CTO.

Interested in consulting? Reach out using the contact page.

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