SoapClient looks like we got no XML document?

Question

SOAP

There is a soap service. I am using a method which returns a pdf file in the response. The problem is that if the request is made in the SoapUI program, then everything is fine, but if through the SoapClient in php, then the error "looks like we got no XML document" is issued. Please tell me where to dig to fix

$client = new SoapClient('url', array(
 'trace' => 1,
'exceptions' => 0)
);

$result = $client->getPdf($wsdl_params);
print_r($result); //SoapFault exception: [Client] looks like we got no XML document in ...