What Links Here Outputs All Records
When the page doesn't exist, too many results.
Special:Whatlinkshere will normally show a list of pages that link to a specified title. However, if the specified title does not exist as an article, the special page finds all links to non-existent pages, rather than the title we specified.
Fixed. The special page had a modified query for this scenario that was not being used. The special page had expected the non-existent thread ID to be -1, when it was actually error.