Insert event in google calender

I guess the root of your problem is that you are using too many includes. Use only include('google-api-php-client-2.0.3/vendor/autoload.php'); and delete the rest of them. I think that the way your code is structured should be enough to create the event, but the way I prefer doing it is this way:

<?php session_start(); //INCLUDE PHP CLIENT LIBRARY require_once "google-api-php-client-2.0.3/vendor/autoload.php"; $client = new Google_Client(); $client->setAuthConfig("client_creds.json"); $client->setRedirectUri('http://' . $_SERVER['HTTP_HOST'] . '/index.php'); $client->addScope("https://www.googleapis.com/auth/calendar"); if (isset($_SESSION['access_token']) && $_SESSION['access_token']) { $client->setAccessToken($_SESSION['access_token']); $cal = new Google_Service_Calendar($client); $event = new Google_Service_Calendar_Event(array( 'summary' => 'Event One', 'location' => 'Some Location', 'description' => 'Google API Test Event', 'start' => array( 'dateTime' => '2016-11-14T10:00:00-07:00' ), 'end' => array( 'dateTime' => '2016-11-14T10:25:00-07:00' ), 'reminders' => array( 'useDefault' => FALSE, 'overrides' => array( array('method' => 'email', 'minutes' => 24 * 60), array('method' => 'popup', 'minutes' => 10), ), ), )); $calendarId = 'primary'; $event = $cal->events->insert($calendarId, $event); printf('Event created: %s\n', $event->htmlLink); } else { if (!isset($_GET['code'])) { $auth_url = $client->createAuthUrl(); header('Location: ' . filter_var($auth_url, FILTER_SANITIZE_URL)); } else { $client->authenticate($_GET['code']); $_SESSION['access_token'] = $client->getAccessToken(); $redirect_uri = 'http://' . $_SERVER['HTTP_HOST'] . '/index.php'; header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL)); } } ?> 

Please note that for the calendar Id value I am using 'primary' because it will be the primary calendar of the authenticated user. Please refer to the documentation here for more details. I hope this helps!

Check all the files that you have include, this may have cause this error. Also you might want to start with PHP Quickstart:

Complete the steps described a simple PHP command-line application that makes requests to the Google Calendar API.

Here is their sample code:

<?php require_once __DIR__ . '/vendor/autoload.php'; define('APPLICATION_NAME', 'Google Calendar API PHP Quickstart'); define('CREDENTIALS_PATH', '~/.credentials/calendar-php-quickstart.json'); define('CLIENT_SECRET_PATH', __DIR__ . '/client_secret.json'); // If modifying these scopes, delete your previously saved credentials // at ~/.credentials/calendar-php-quickstart.json define('SCOPES', implode(' ', array( Google_Service_Calendar::CALENDAR_READONLY) )); if (php_sapi_name() != 'cli') { throw new Exception('This application must be run on the command line.'); } /** * Returns an authorized API client. * @return Google_Client the authorized client object */ function getClient() { $client = new Google_Client(); $client->setApplicationName(APPLICATION_NAME); $client->setScopes(SCOPES); $client->setAuthConfig(CLIENT_SECRET_PATH); $client->setAccessType('offline'); // Load previously authorized credentials from a file. $credentialsPath = expandHomeDirectory(CREDENTIALS_PATH); if (file_exists($credentialsPath)) { $accessToken = json_decode(file_get_contents($credentialsPath), true); } else { // Request authorization from the user. $authUrl = $client->createAuthUrl(); printf("Open the following link in your browser:\n%s\n", $authUrl); print 'Enter verification code: '; $authCode = trim(fgets(STDIN)); // Exchange authorization code for an access token. $accessToken = $client->fetchAccessTokenWithAuthCode($authCode); // Store the credentials to disk. if(!file_exists(dirname($credentialsPath))) { mkdir(dirname($credentialsPath), 0700, true); } file_put_contents($credentialsPath, json_encode($accessToken)); printf("Credentials saved to %s\n", $credentialsPath); } $client->setAccessToken($accessToken); // Refresh the token if it's expired. if ($client->isAccessTokenExpired()) { $client->fetchAccessTokenWithRefreshToken($client->getRefreshToken()); file_put_contents($credentialsPath, json_encode($client->getAccessToken())); } return $client; } /** * Expands the home directory alias '~' to the full path. * @param string $path the path to expand. * @return string the expanded path. */ function expandHomeDirectory($path) { $homeDirectory = getenv('HOME'); if (empty($homeDirectory)) { $homeDirectory = getenv('HOMEDRIVE') . getenv('HOMEPATH'); } return str_replace('~', realpath($homeDirectory), $path); } // Get the API client and construct the service object. $client = getClient(); $service = new Google_Service_Calendar($client); // Print the next 10 events on the user's calendar. $calendarId = 'primary'; $optParams = array( 'maxResults' => 10, 'orderBy' => 'startTime', 'singleEvents' => TRUE, 'timeMin' => date('c'), ); $results = $service->events->listEvents($calendarId, $optParams); if (count($results->getItems()) == 0) { print "No upcoming events found.\n"; } else { print "Upcoming events:\n"; foreach ($results->getItems() as $event) { $start = $event->start->dateTime; if (empty($start)) { $start = $event->start->date; } printf("%s (%s)\n", $event->getSummary(), $start); } } 

This shows what are the needed files to be included. Hope this helps.