CakePHP 3 Soap Server Error - php

Question

I try to create a Soap Server in CakePHP 3 but if I want to connent with my client i become error's every time.
I set up the server in a function:
public function view($id) {
$connection = ConnectionManager::get('default');
$user = $connection->execute('SELECT * FROM users WHERE id='.'"'.$id.'"')->fetchAll('assoc');
$obj = new Post;
$this->viewBuilder()->layout = false;
$this->autoRender = false;
ini_set("soap.wsdl_cache_enabled",0); //disable wsdl cache
$server = new SoapServer(null, array(
'uri' => 'http://localhost/test-uri',
'encoding'=>'UTF-8'
)
);
$server->setObject($obj);
$server->handle();
}
in a model I create this function:
namespace App\Model\Entity;
use Cake\ORM\Entity;
use Cake\Utility\Xml;
class Post {
function testfunktion($param){
return $param;
}
}
my client script show this:
$soap = new SoapClient(
null,
array(
"location" => "http://localhost/shop_system/users/view/2",
"uri" => "http://test-uri",
"trace" => 1
)
);
try {
$product = $soap->testfunktion("Michael");
} catch (SoapFault $e) {
echo $e;
print($soap->__getLastResponse());
}
and this is my output:
SoapFault exception: [Client] looks like we got no XML document in C:\xampp\htdocs\shop_system\webroot\client.php:15 Stack trace: #0 C:\xampp\htdocs\shop_system\webroot\client.php(15): SoapClient->__call('testfunktion', Array) #1 C:\xampp\htdocs\shop_system\webroot\client.php(15): SoapClient->testfunktion('Michael') #2 {main}
Notice (8): Undefined index: HTTP_ACCEPT_LANGUAGE [APP/Controller\UsersController.php, line 22]Michael
i dont know what i must do by this error