Warning: session_start() in php session

Question

I am getting the following error in my application that asks the user to login using facebook account : Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at XXXXXXXXXXXXXXXXXXXXXXXXXXXXX/fblogin1.php:4) in XXXXXXXXXXXXXXXXXXXXXXXXXXXXX/lib/facebook.php on line 37

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at XXXXXXXXXXXXXXXXXXXXXXXXXXXXX/fblogin1.php:4) in XXXXXXXXXXXXXXXXXXXXXXXXXXXXX/lib/facebook.php on line 37

I don't know why this error is shown in spite of the face that it does not appear when I was hosting my app on phpcloud.com

Here is the code of the fblogin1.php

    <?php
    $id=$_GET['id'];
    include('lib/db.php');
    require 'lib/facebook.php';
    require 'lib/fbconfig.php';

    // Connection...
    $user = $facebook->getUser();
    if ($user)
     {
     $logoutUrl = $facebook->getLogoutUrl();
     try {
     $userdata = $facebook->api('/me');
     } catch (FacebookApiException $e) {
    error_log($e);
    $user = null;
     }
    $_SESSION['facebook']=$_SESSION;
    $_SESSION['userdata'] = $userdata;
    $_SESSION['logout'] =  $logoutUrl;
    header("Location: home.php?id=$id");
    }
    else
    { 
    $loginUrl = $facebook->getLoginUrl(array( 'scope' => 'user_about_me,user_activities,user_birthday,user_checkins,user_education_history,user_events,user_groups,user_hometown,user_interests,user_likes,user_location,user_notes,user_online_presence,user_photo_video_tags,user_photos,user_relationships,user_relationship_details,user_religion_politics,user_status,user_videos,user_website,user_work_history,email,read_friendlists,read_insights,read_mailbox,read_requests,read_stream,xmpp_login,ads_management,create_event,manage_friendlists,manage_notifications,offline_access,publish_checkins,publish_stream,rsvp_event,sms,publish_actions,manage_pages'
    ));
    echo '<div class="style1"><a target="_top" href="'.$loginUrl.'"><img src="facebook.png" title="Login with Facebook" /></a></div>';
     }
     ?>

Here is the facebook.php code :

    <?php
     ob_start();
     ?>
     <?php
     require_once "base_facebook.php";
     class Facebook extends BaseFacebook
     {
       public function __construct($config) {
         if (!session_id()) {
           session_start();
         }
         parent::__construct($config);
       }

       protected static $kSupportedKeys =
         array('state', 'code', 'access_token', 'user_id');
       protected function setPersistentData($key, $value) {
         if (!in_array($key, self::$kSupportedKeys)) {
           self::errorLog('Unsupported key passed to setPersistentData.');
           return;
         }
         $session_var_name = $this->constructSessionVariableName($key);
         $_SESSION[$session_var_name] = $value;
       }
       protected function getPersistentData($key, $default = false) {
         if (!in_array($key, self::$kSupportedKeys)) {
           self::errorLog('Unsupported key passed to getPersistentData.');
           return $default;
         }
         $session_var_name = $this->constructSessionVariableName($key);
         return isset($_SESSION[$session_var_name]) ?
           $_SESSION[$session_var_name] : $default;
       }

       protected function clearPersistentData($key) {
         if (!in_array($key, self::$kSupportedKeys)) {
           self::errorLog('Unsupported key passed to clearPersistentData.');
           return;
         }
         $session_var_name = $this->constructSessionVariableName($key);
         unset($_SESSION[$session_var_name]);
       }
       protected function clearAllPersistentData() {
         foreach (self::$kSupportedKeys as $key) {
           $this->clearPersistentData($key);
         }
       }
       protected function constructSessionVariableName($key) {
         return implode('_', array('fb',
                          $this->getAppId(),
                          $key));
       }
     }
     ?>

I have found a leading thread in this post (What is output buffering?) that states that outputbuffering is a solution to such problems. If so, where shall I add it ? in show.php or facebook.php and how to add it ? NB : I have added in the beginning
and this in end but this didn't work for me

Where is your session_start() in which file? Check that there's no output before and no header() call. — Maarkoize, Dec 27 '13 at 13:34

score 0 · Answer 1 · answered Dec 27 '13 at 13:35

0

Make sure your 'lib/facebook.php' isn't writing any output to the screen... no echo commands, etc. What the error is telling you is that nothing can be written prior to the header() being sent. It's also telling you that something is being written in Facebook.php on line 37.

answered Dec 27 '13 at 13:35

Charlie74

2,883
15
23

in facebook.php on line 37 here is the code `code` public function __construct($config) { if (!session_id()) { session_start(); } parent::__construct($config); }`code` – Nizar Bark Dec 27 '13 at 13:37
I have just edited my question could you please have a look at it ? – Nizar Bark Dec 29 '13 at 15:25

Warning: session_start() in php session

1 Answers1