After Magento update to 2.4, I'm getting this "base is not a constructor" error which is causing other grids to unable load in the admin. When I run the command: ->sudo chmod 777 -R Var/ pub/static/ generated then cache flush error stopped showing but it starts showing again when I navigate other admin pages.

Please suggest some solution. Any help will be appreciated.

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1 Answer 1


It's hard to know what the solution is exactly without more information. However, I've seen this exact error occur when there is a problem in the JS extending a widget somewhere... like when the widget targeted for being extended doesn't exist. Perhaps it wasn't returned by the JS file that creates the widget.

In your case, perhaps one of your modules or your theme is trying to extend a widget that no longer exists or is changed in some way. You may want to try switching to the Blank theme and see if that solves the issue, if so the issue resides in your theme somewhere. If that doesn't solve it, disable custom and third-party modules little by little until you track down which one is causing the issue.

  • Yeap, it's seems like your application trying to load some js component that is changed/deleted etc. Try to debug mixins.js step by step to find which one is leads to an error. Nov 15, 2022 at 22:04

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