Thread:Thundermaker300/@comment-32003810-20171020022609/@comment-4196050-20171020024012

What category were you trying to add? That filter catches you when you try to post a category that only an infobox should add (like Category:2008 players). Many of our categories are managed by templates or infoboxes, so that if information is updated to that template (such as you enter the wrong date and need to move a user's join date from 2013 to 2014), you don't need to manually change the category for you (the template will do it for you).