wsdl接口调用错误：SoapFault: BEA-380001: Internal Server Error

Question

调用WSDL接口时出错，print_r($client->__getFunctions());结果为

Array
(
    [0] => base64Binary applyExecute(base64Binary $xml)
)

调用代码：

$xml = "<?xml version="1.0" encoding="UTF8"?><request></request>";
$xml = base64_encode($xml);
try{
    $wsdl = "http://xxx?wsdl";
    $client = new SoapClient($wsdl);    
    $res = $client->applyExecute($xml);
}catch (SoapFault $e){
    print_r($client);
}

错误信息：