Thread:Extension talk:Pdf Export/Error after upgrade to MediaWiki 1.21.0/reply

Well, wfLoadExtensionMessages has just been removed from GlobalFunctions.php. It has been replaced by wfMsgExt which has been replaced by wfMessage. See Manual:Messages_API. After replacing wfLoadExtensionMessages by wfMessage this extension works again. However, don't know the purpose of the original wfLoadExtensionMessages call at all, since I am not familiar with the MW API.