Can't set cookie in Wordpress plugin after theme has started rendering

Question

When I set a cookie in a Wordpress plugin, I get the "headers already sent" error. Can someone suggest how I can fix this?

Warning: Cannot modify header information – headers already sent by (output started at /home/content/53/7742253/html/wordpress/wp-content/themes/twentyten/header.php:11) in /home/content/53/7742253/html/wordpress/wp-includes/pluggable.php on line 692,693,694

my code:-

     if(isset($_REQUEST['id']) && !is_user_logged_in())

      {

         require_once( ABSPATH . WPINC . '/registration.php' );


    $registration = get_option( 'users_can_register' );

       global $wpdb;

       $user_id = $wpdb->get_var( $wpdb->prepare("SELECT user_id FROM              

                  $wpdb->usermeta           WHERE 

                meta_key = 'id' AND meta_value =%s",$id) );

         if ( empty($user_id) ) 
              {

                 $wp_user_obj = get_user_by('email', $email);

                $user_id = $wp_user_obj->ID;

               }

               if ( $user_id)

                  {

                   wp_set_auth_cookie( $user_id );

                      wp_set_current_user( $user_id );

               if ( isset( $_REQUEST['redirect_to'] ) && !empty( 
           $_REQUEST['redirect_to'] ) ) 
            {

              wp_redirect( home_url() );

                 }
                 else 
               {

                wp_redirect(home_url() );

                 }

                   }      

                     else

                   {

                   $userdata = array();


                $user_id = wp_insert_user($userdata );

                 wp_new_user_notification($user_id,$user_pass);

                  if ( $user_id )
                     {

                         $creds = array();

                        $creds['user_login'] = $username;

                         $creds['user_password'] = $user_pass;

                          if ( !empty( $remember ) )
                            { 

                             $creds['remember'] = true;

                                 }

                    $user = wp_signon( $creds, true );  

                     update_usermeta( $user_id,'id',esc_attr( $_REQUEST['id']));

                 update_usermeta( $user_id,'fname',esc_attr( $_REQUEST['fname']));

                   update_usermeta( $user_id,'lname',$_REQUEST['lname']);

              update_usermeta( $user_id, 'email',esc_attr( $_REQUEST['email']) );

                 wp_redirect(home_url() );

               }

                }

               }    

             global $user_ID; $user = get_userdata( $user_ID );

           if(is_user_logged_in())
         {

                echo $user->user_login ; 

              } 



and heder.php line:-  `<html <?php language_attributes(); ?>>`

Make sure that there is no kind of output before setting the cookie, maybe a blank line or another module already outputting something. — Quasdunk
I wonder if we have some sort of FAQ for the PHP Headers already sent scenario caused by using header, session or set_cookie. — hakre
Possible duplicate of: stackoverflow.com/search?q=Cannot+modify+header+information+php — hakre

hakre hakre · Accepted Answer · 2011-08-06T08:56:03

You're calling your set_cookies function too late. At the time you call it, output has already started. You need call it before any output has started, because cookies can not be set if output has already started (see as well: setcookie^Docs).

In your case before header.php line 11 is being executed.

That's merely before the theme get's loaded.

Can't set cookie in Wordpress plugin after theme has started rendering

2 Answers