After updating from MW 1.23 to 1.24 the extension stopped working (using the htmldoc converter) due to method userCanRead() not existing any more. In order to work under MW 1.24 I had to change file PdfExport/converters/HtmlDocPdfConverter.php from
if (is_null($title) || !$title->userCanRead()) {
to
if (is_null($title) || !$title->userCan('read')) {