Get coordinates from address

hi i try to get coordinates from openstreetmap
this is my code :

Code:

    public function getCoordinateFromAddress()
    {
     
   
        $address = 'piazza della signoria  ,5, firenze ';

        $geocode = file_get_contents('https://nominatim.openstreetmap.org/search?q='.$address.'&format=json&polygon=1&addressdetails=1');

        $output= json_decode($geocode);

        //print_r($output);
        //die();

        $lat = $output->results[0]->geometry->location->lat;
        $long = $output->results[0]->geometry->location->lng;

   
   }

but with this code i have :

Code:

file_get_contents(https://nominatim.openstreetmap.org/search?q=piazza della signoria ,5, firenze &format=json&polygon=1&addressdetails=1): Failed to open stream: HTTP request failed! HTTP/1.1 400 Bad Request

How can i solve ?