PHP Header(Location: ...): Force Url Change in Address Bar

PHP Redirect to different url using header( Location: ) does not work

Headers must be set before any data is transmitted, so you can't just stick them in the middle of a file. Quoting the the manual:

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.

So at the very least you'll need to rewrite your file to:

<?php

  header("Window-target: _parent");
  header("Location: https://www.w3schools.com/");

?>
<!doctype html>
...

Also, never sleep() in an http(s) response: that response should finish as fast as it can, no matter what content it needs to generate. Sleep has no place in (really any) PHP code.

php - header location - wrong url opening

<?php
/* Redirect to a different page in the current directory that was requested */
$host  = $_SERVER['HTTP_HOST'];
$uri   = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
$extra = 'mypage.php';
header("Location: http://$host$uri/$extra");
exit;
?>

http://php.net/manual/en/function.header.php

Unable to persist address in browser URL bar, during PHP 302 Redirect

What am I missing to ensure the page redirects (via a 302 Redirect) without the browser URL bar location updating?

Nothing. That's how HTTP redirects work.

If you want to preserve the URL, then you need to perform an internal redirect or a proxy request so that the server returns the content you want for the URL that was requested.

Address Bar not changing - PHP

Define

define('DIRADMIN','localhost/v2/admin/);

define('DIRADMIN','http://localhost/v2/admin/');

PHP Redirect user and save previous URL in browser's history

Although I'm still questioning the reason, but you maybe able to use javascript on page A for redirection. In this way we are able to get back to where we were on back click.

So here we have a js script that only runs if a php condition is false:

<?php
if ( ! condition) { ?>
    <script>
        window.location.href = "http://example.com/B";
    </script>
<? }
?>