I managed to figure out how to solve this, but thought it was worth reporting.
I attempted to assign a parent category, cat-B, to cat-A which already had 3 subcategories in it. The Discourse system gave me an error message and said something like ‘we can’t move subcategories’. So I’m guessing there’s a limit to how many categories can be nested within each other.
I concluded that’s fine, I’ll just reassign the parent category for the 3 subcategories first. But when I tried to do that, I got an exception error like this.
The console gives a 404 error for the URL ending in
A similar error shows up for the other 2 subcategories of cat-A.
What it should show instead is
c/cat-A/subcategory/edit without the
cat-B. So I manually typed the URL with this format and got to the normal category settings page as expected. I was able to fix all 3 subcategories and cat-A in this way.
This is probably just a small bug that would be worth fixing in the future