I was updating MediaWiki to 1.17 last night, and kept getting a::
Fatal error: Call to undefined function wfWarn() in /var/www/w/extensions/SemanticMediaWiki/includes/SMW_Setup.php on line 49
because I was setting up SMW with $wgServerName:
require_once("$IP/extensions/SemanticMediaWiki/SemanticMediaWiki.php");
enableSemantics($wgServerName);
and this has been deprecated in 1.17. As for why SMW is using the nonexistant mfWarn(), I haven’t got time to investigate.