Thread:Extension talk:InviteSignup/404 on form submission after "add" button click/reply

And there was the bullet: SpecialInviteSignup.php line 147 Html::hidden( 'title', $this->getPageTitle->getDBKey ).

cuz of Wiki.php line 77: $title = $request->getVal( 'title' );

PS: im using latest wiki and extension versions on the post date.