I had this error too and thanks to your help rullator, it’s fine.
But I get another error message whenever the YAPB sidebar widget is in use. The message displays directly on the right in the sidebar:
Warning: Parameter 1 to YapbSidebarWidget::onDrawLocal() expected to be a reference, value given in /var/www/XXXXX/html/blog/wp-includes/widgets.php on line 891
Any help?
Edit
Ok found it myself.
I changed the line
function onDrawLocal($args) {
to
function onDrawLocal(args) {
in
yapb-sidebar-widget\YapbSidebarWidget.class.php