I tried to change the slug of a category to “internet” in wordpress and got the wordpress message saying “Category not updated“. I did a little research and found that the category slugs can’t be the same as tag slugs (in the wp-terms table).
Here is what you have to do, Click Tags tab in your wordpress admin panel, search for the slug and delete it from the tags. Go back to categories and change the slug you should be fine.

Ahhh you’re the man. Thanks
Thanks!
I think you’ll find the same is true if you have a page or post with the same slug. This happened to me recently when both the category slug and a page slug were the same.
Many thanks that saved me some time 🙂