AdWords API expired cookie error

Question

I am trying to build an "as simple as possible" routine to retrieve AdWords campaign names.

However, I am getting this error message

AuthenticationError.LOGIN_COOKIE_REQUIRED @ ; trigger:'<null>'

whenever I run the following PHP script for the first time.

Subsequent runs work fine for some hours until I get the error again (I believe the referred cookie expires again).

What is this cookie about? Can someone pinpoint what is going on and how to fix it?

<?php

$refreshToken=/* omitted */;
$clientId=/* omitted */;
$clientSecret=/* omitted */;
$clientCustomerId=/* omitted */;
$developerToken=/* omitted */;

$ch=curl_init('https://accounts.google.com/o/oauth2/token');
curl_setopt($ch,CURLOPT_HEADER,false);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
curl_setopt($ch,CURLOPT_CUSTOMREQUEST,'POST');
curl_setopt($ch,CURLOPT_POSTFIELDS,http_build_query(array(
    'refresh_token'=>$refreshToken,
    'client_id'=>$clientId,
    'client_secret'=>$clientSecret,
    'grant_type'=>'refresh_token',
)));
$json=curl_exec($ch);
curl_close($ch);
$object=json_decode($json);
$accessToken=$object->access_token;

$namespace='https://adwords.google.com/api/adwords/cm/v201309';
$soapClient=new SoapClient($namespace.'/CampaignService?wsdl',array(
    'features'=>SOAP_SINGLE_ELEMENT_ARRAYS,
    'encoding'=>'utf-8',
    'stream_context'=>stream_context_create(array(
        'http'=>array(
            'header'=>'Authorization : Bearer '.$accessToken,
        ),
    )),
));
$soapClient->__setSoapHeaders(new SoapHeader($namespace,'RequestHeader',array(
    'clientCustomerId'=>$clientCustomerId,
    'developerToken'=>$developerToken,
    'userAgent'=>'TestApp',
    'validateOnly'=>false,
    'partialFailure'=>false,
)));
try
{
    $result=$soapClient->get(array(
        'serviceSelector'=>array(
            'fields'=>array('Name'),
        ),
    ));
}
catch (SoapFault $e)
{
    $result=$e->getMessage();
}
var_dump($result);

Answer 1

Not sure why this happens. First call the error always happens, probably due to WSDL loading. Afterwards it can be mitigated by increasing the WSDL cache ttl:

$ttl=ini_get('soap.wsdl_cache_ttl');
ini_set('soap.wsdl_cache_ttl',100*365*24*60*60); // 100 years
$soapClient=new SoapClient($namespace.'/CampaignService?wsdl',array(
    'features'=>SOAP_SINGLE_ELEMENT_ARRAYS,
    'encoding'=>'utf-8',
    'cache_wsdl'=>WSDL_CACHE_BOTH,
    'stream_context'=>stream_context_create(array(
            'http'=>array(
                    'header'=>'Authorization : Bearer '.$accessToken,
            ),
    )),
));
ini_set('soap.wsdl_cache_ttl',$ttl);