Thread:Project:Support desk/Fatal error: Call to a member function addWikiMsg() on a non-object in /home/username/public html/wiki/includes/specials/SpecialLinkSearch.php on line 82/reply (18)

Its hard to tell because I can't re-create it on my local install. Possibilities always includes things like somehow one uploading mediawiki you had an older version of a specific php file instead of the version that goes with your version (rare, but does happen)

Is your wiki public? if you provide a url I might be able to tell you more.