upload a file to my web directory

I'm trying to upload a file (png) to my web directory using an URL:

$url = "http://api.qrserver.com/v1/create-qr-code/?data=hello_word&size=100x100";
$file = file_get_contents($url);
$fileName = "filename";
$dir = $this->get('kernel')->getRootDir() . '/../web/uploads/img';
$file->move( $dir , $fileName);

Warning: file_get_contents(http://api.qrserver.com/v1/create-qr-code/?data=hello_word&size=100x100): failed to open stream: HTTP request failed! HTTP/1.1 400 Bad Request