Invlid_grant When trying to refresh token - Google Oauth - PHP - php

Question

just started using google admin SDK,trying to retrieve specific user's infomation.
i keep getting the same error over and over
[29-May-2015 14:41:18 Africa/Tunis] PHP Fatal error: Uncaught
exception 'Google_Auth_Exception' with message 'Error refreshing the
OAuth2 token, message: '{ "error" : "invalid_grant"
during my research i found that it's mostly a syncing problem(server time)
but my web app is hosted on a third party server.checked my service account credentials
Ps: don't know if it matters but the server's time zone is GMT+1
`
<?php
require 'src/Google/autoload.php';
session_start();
$timestamp = $_SERVER['REQUEST_TIME'];
echo gmdate("Y-m-d\TH:i:s\Z", $timestamp);
$service_account_name = "xx";
$key_file_location = "yyy.p12";
$client = new Google_Client();
$client->setApplicationName("Members");
$directory = new Google_Service_Directory($client);
if (isset($_SESSION['service_token']) && $_SESSION['service_token']) {
$client->setAccessToken($_SESSION['service_token']);
}
$key = file_get_contents($key_file_location);
$cred = new Google_Auth_AssertionCredentials(
// Replace this with the email address from the client.
$service_account_name,
// Replace this with the scopes you are requesting.
array('https://www.googleapis.com/admin/directory/v1/users'),
$key,
'notasecret'
);
$cred->sub = "admin-email";
$client->setAssertionCredentials($cred);
if ($client->getAuth()->isAccessTokenExpired()) {
$client->getAuth()->refreshTokenWithAssertion($cred);
}
$_SESSION['service_token'] = $client->getAccessToken();
$email = "personto lookfor-email";
$r = $dir->users->get($email);
if($r) {
echo "Name: ".$r->name->fullName."<br/>";
echo "Suspended?: ".(($r->suspended === true) ? 'Yes' : 'No')."<br/>";
echo "Org/Unit/Path: ".$r->orgUnitPath."<br/>";
} else {
echo "User does not exist: $email<br/>";
// if the user doesn't exist, it's safe to create the new user
}
`

Answer 1

The reason of the "Invalid grant" error may be due to the refresh token not working. This happens When the number of refresh tokens exceeds the limit, older tokens become invalid. If the application attempts to use an invalidated refresh token, an invalid_grant error response is returned. Here is the link for more documentation.