We have a category in RQM for Feature and want to create a sub category (sub feature). However, when I attempt to do this I get an empty error message. I can add the new category (sub feature) and save just fine, but when I select 'Create Subcategory' and choose sub feature to be under the existing Feature category, the error message occurs.

I have tried just adding the sub feature (no values in that new category) and I still get the error. Unfortunately, the error message being empty tells me nothing about the cause, so I can't give you any details other than the behavior in the RQM client.

BTW - I can create a new Feature category and a new sub feature category with values and set them up to filter sub feature selections based on the feature selection. The issue appears to be when trying to set this up with the existing feature category.