Im having no luck finding the solution to this problem that others have had over the course of a few years. Suddenly the category manager stops working, leaving the screen blank and impossible to add, enter into or work with categories. The only thing that works is expand all.
A look at the consol reveals these errors:
I'm a magento newbie but I have plenty of experience with php/mysql. Everything was working fine. I removed a theme that I was not happy with and installed another, Other than than haven't touched core files.
Solved! Go to Solution.
I only found one other person reporting this issue: https://stackoverflow.com/questions/42208503/magento-issue-catalog-category-productsjsobject-is-not-....
I would concur with the commentors suggestion on stackoverflow: This is going to be from a customisation, most likely from a third party module but it could be a custom one that's been built for the site too. I would start by disabling modules in app/etc/modules/ folder, see that it works and gradually re-enable each one until it breaks.