Having Issue on Redirecting With Session in WordPress-CodePudding

I am trying to create a simple login system in WordPress using core PHP but I am getting this error message

Warning: Cannot modify header information - headers already sent by (output started at /www/www/www/wp-content/themes/mytheme/header.php:20) in /www/www/www/wp-content/themes/mytheme/page-solutions.php on line 9

In the header.php template I have

<?php
session_start();
/**
 * The header.
 *
 */
?>
<!doctype html>
<html lang="en">
<head>
...

and in the page-solutions.php page

<?php
/**
 * Template Name: Solutions
 *
 */
get_header();

if(!isset($_SESSION["loggedin"]) || $_SESSION["loggedin"] !== true){
header("location: home");
exit;
}

As you can see I am trying to redirect not logged users to front-page.php which I called it Home but I am getting error on header("location: home"); Can you please let me know how to fix this?

CodePudding user response：

Functions that modifies headers must be called before any output is made. In this case you're calling get_header() functions which sends an output, and then youre trying to modify the header. Try changing the order that you execute the code, like this:

<?php
/**
* Template Name: Solutions
*
*/

 if(!isset($_SESSION["loggedin"]) || $_SESSION["loggedin"] !== true){
 header("location: home");
 exit;
 }

 get_header();