Warning: Cannot modify header information - headers already sent by...header refresh, redirect

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Headers already sent by PHP

I am getting this error when I try to redirect after running a user login script.

It attempts to change the header data at this line:

header("Refresh: 2; url=index.php");

This is the full login.php script.

<?php 
session_start();
require_once('init.php');

$username = trim($_POST['username']);
// create a new object
$login = new Auth($_POST, $dbh);

    if($login->validateLogin()){

        $_SESSION['loggedin'] = true;
        $_SESSION['username'] = $username;
        $list = $login->getUserInfo();
        $_SESSION['id'] = $list['id'];
        $_SESSION['thumb'] = $list['img_thumb'];

        echo '<div class="content">';
        echo '<h1>Thank you for logging in '.$username.'. Redirecting...</h1>';
        echo '</div>';
        header("Refresh: 2; url=index.php");

    }else{

        echo '<div class="content">';
        echo '<h1>Sorry but we didn\'t recognise those login details, please try again.</h1>';
        echo '</div>';

    }



require_once('inc/footer.inc.php');
?>

The init.php file calls the header.php containing the html5 doctype, meta tags etc.

How can I redirect the user to the index page after logging them in and send the header information as usual?

I'd like there to be a delay in the redirect. Plus that gives the same error using location. — crmepham, Jul 23 '12 at 15:23
The Location header takes an absolute URI, not a relative one (even if most browsers will error correct). — Quentin, Jul 23 '12 at 15:23
@crm — Good rules of thumb: Either a message is worth displaying until the user clicks a link to move forwards, or it isn't worth displaying at all. — Quentin, Jul 23 '12 at 15:24

score 3 · Accepted Answer · answered Jul 23 '12 at 15:23

From the PHP docs.

Remember that header() must be called before any actual output is sent, either by normal HTML tags, blank lines in a file, or from PHP.

If you want the page to redirect after a few seconds you will need to use Meta Refresh.

<meta http-equiv="refresh" content="5;URL='http://example.com/'">

score 0 · Answer 2 · answered Jul 23 '12 at 15:23

Simply move the header() call before any echo statements:

<?php
/* ... */
if($login->validateLogin()){

    $_SESSION['loggedin'] = true;
    $_SESSION['username'] = $username;
    $list = $login->getUserInfo();
    $_SESSION['id'] = $list['id'];
    $_SESSION['thumb'] = $list['img_thumb'];

    header("Refresh: 2; url=index.php"); // Put this *before* any output
    echo '<div class="content">';
    echo '<h1>Thank you for logging in '.$username.'. Redirecting...</h1>';
    echo '</div>';

}else{

    echo '<div class="content">';
    echo '<h1>Sorry but we didn\'t recognise those login details, please try again.</h1>';
    echo '</div>';

}
/* ... */

score 0 · Answer 3 · answered Jul 23 '12 at 15:24

Using echo and then trying to set a header for Location will always raise that error. ¿What could be better to let the user know about redirect than redirecting them? If you want to show such message (this approach would not show it for a whole second if it ever worked), you should use javascript to update content and use some kind of delay...

... but perhaps it's too much work. If you show a welcome message after login, it should be enough, right? :)

Warning: Cannot modify header information - headers already sent by...header refresh, redirect

3 Answers3