Joost de Valk gives the solution in an another post :
Bug found and fixed for the next release, you can fix it for your site for now by going into frontend/class-opengraph.php and changing line 32 to:
$this->options = get_wpseo_options();
Joost de Valk gives the solution in an another post :
Bug found and fixed for the next release, you can fix it for your site for now by going into frontend/class-opengraph.php and changing line 32 to:
$this->options = get_wpseo_options();