Using Magento 2.3.3 seeing the below notice in our browser console.

Fallback to JQueryUI Compat activated. Your store is missing a dependency for a jQueryUI widget. Identifying and addressing the dependency will drastically improve the performance of your site. Compat.js

Could anyone provide any guidance on where to start to debugging this issue


  • 3
    Yeah the jquery/ui is not recommended in 2.3.x and has been split into modules to improve javascript performance. I would just get grep for jquery/ui in app folder and see what files are using it and start swapping out for modules. The original source files should show you what the modules that can be used instead are and just replicate.
    – harri
    Commented Oct 25, 2019 at 15:34
  • i just installed a clean 2.3.3 and i found oodles of 'jquery/ui' grepping through the code base
    – iphigenie
    Commented Oct 27, 2019 at 18:46
  • I can see define([ ....... 'jquery/ui', ...... ] most of the module in 2.3.4 what do i do ? Commented Mar 11, 2020 at 10:39

3 Answers 3


I am facing the same issue currently and working on it, but it is highly specific per site and the issue might be connected with your theme, extensions and custom code.

The issue is caused by certain JS or PHTML files calling jquery/ui as a dependency like this:


So to deal with the issue, you need to do a text search for jquery/ui on all files located in app/code and app/design/frontend/{vendor}/{theme}/.

You need to figure out which module of jquery/ui is needed in each particular instance you find.

Here is a list of all jQuery UI modules (you can see them when you open compat.js in the console warning message)


Magento is basically loading all jQuery UI modules because it can't identify which one(s) the custom code needs.

This slows down the site and you should definitely fix it.

To fix it, you need to:

  1. Locate which files are calling jquery/ui

  2. If this is a customization of original Magento functionality, you can probably check the original Magento vendor files and compare which jQuery UI module you need --> then you just change the jquery/ui dependency with the exact module that is needed.

  3. For extensions, this might be difficult because you need to figure out which module of jQuery UI the extension is using. The easiest fix would be to update the extension.

  • it seems all over the core code. Mostly across the admin code base but also in magento/module-theme/view/frontend/requirejs-config.js and the dotmailer and amazon "imposed" modules And the Stripe integration too :(
    – iphigenie
    Commented Oct 27, 2019 at 18:44
  • @iphigenie can't say for sure, but most probably not all core modules were adjusted to this recent change, but will change in a future version of Magento. It's also possible that the admin area still uses jquery/ui as a non-modular dependency.
    – Lez
    Commented Oct 27, 2019 at 22:15
  • Which plugins from these should be used to achieve smartheader, stickyheader and expandingsearch functionalities? Any help would be highly appreciated.
    – Zoya
    Commented Dec 12, 2019 at 18:50
  • 1
    @Zoya although I can imagine what these functionalities do, it's impossible for me to know exactly how your theme used jquery/ui for them without seeing the code. I can suggest this though: since (from my experience) theme developers usually have unnecessary or poorly written code I would suggest to first try and remove jquery/ui and check if everything is working. If you get JS errors, try adding the core and/or widget modules.
    – Lez
    Commented Dec 12, 2019 at 19:33
  • @Lez I am using Ultimo theme and the developer has abandoned updating after magento 2.3.1.
    – Zoya
    Commented Dec 14, 2019 at 9:44

The answer from Lez is absolutely correct. But there is a much easier way to locate the extension which is causing it by using google chrome.

Just open the developer tools, and you will see something like this:

enter image description here

You have to extend it and debug the stack trace:

enter image description here

it will lead you to the initial call, which might hint the module, in my case Amasty_HidePrice

enter image description here

then contact the company which developed the module and tell them to fix it or fix it yourself in an override.

If you still can't find the extension, then you have to disable the extensions one by one until you find the one which causes the error.

  • I am not getting this option i can't find out what causing the issue as in which module Commented Mar 11, 2020 at 10:29
  • Try it again with chrome
    – Black
    Commented Mar 11, 2020 at 10:51
  • 1
    i did on chrome but not able to get the way you have Commented Mar 12, 2020 at 10:33
  • @jibingeorge, which version of chrome? Maybe you need to update. Otherwise your error might be different than mine.
    – Black
    Commented Mar 12, 2020 at 11:21
  • 1
    It has always be Amasty the problem and will always be Commented Aug 15, 2022 at 16:19

I also can to confirm that Amasty company likes to produce deprecated features like a discussed one: http://screenshots.collabstar.com/vza/Selection_2e19d30.png That's an interesting fact they mark the issue as "jquery/ui" //can't be removed . I communcate with them on a fix. Another candidate module is Ebizmarts Mailchimp with a script "campaigncatcher.js"

  • 1
    So, what was the fix? Commented Dec 3, 2020 at 1:42
  • Amasty company likes to produce broken and unmaintanable software Commented Aug 15, 2022 at 16:55

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