After upgrading a Magento 2.x project to Magento 2.4.8, I encountered an issue where legacy admin functionality that depends on ExtJS (specifically ext-tree-checkbox.js) is no longer working. The following error is thrown in the browser console:
Error ext-tree-checkbox.js:5 Uncaught ReferenceError: Ext is not defined
It appears that Magento 2.4.8 has removed the built-in ExtJS libraries, including:
ext-tree.js
ext-tree-checkbox.js
and other related ExtJS files
This breaks older modules that use ExtJS-based category trees or checkbox trees in the admin panel.
What is the recommended alternative for extjs/ext-tree-checkbox in Magento 2.4.8?
If you have any idea or experience implementing this in Magento 2.4.8, please let me know.