I have a category with 27 sub-categories. When I try to reorder them, I receive “422 Unprocessable Entity” upon saving.
I haven’t been able to reproduce this. Can you try reordering the categories with your browser’s inspector open to its console tab and see if any more details about the error show up there?
I can’t do that now, but will ASAP. In the meantime, I upgraded to the latest Discourse 2.4.0.beta5 (302e8f4393) and the 422 error evolved to
422 No Reason Phrase.