PHP failed to redirect after successful login

Question

I've been trying to redirect the user to the Userpanel.php page after a successful login, but header() method doesnt work in the if condition. Here is the code:

    <?php

    $db_host="localhost";
    $db_name="researchblog";
    $db_user="root";
    $db_pass="";
    $conn=mysqli_connect($db_host, $db_user, $db_pass);
    mysqli_select_db($conn,$db_name);

    if(isset($_POST['username']))
    {
        $uname=$_POST['username'];
        $password=$_POST['password'];

        $sql="select * from users where username='".$uname."' AND password ='".$password."'";

        $result=mysqli_query($conn,$sql);
        if(mysqli_num_rows($result)==1)
        {
            header("location:Userpanel.php");

        }
        else
        {
            echo "<script> alert('Failed to Login') </script>";

        }
    }

?>

Don't store plain passwords in the DB, you should use `password_hash()` and `password_verify()`. — Barmar, Apr 10 '19 at 16:22
You should also use prepared statements to protect against SQL injection. — Barmar, Apr 10 '19 at 16:23
@Moon try this and refresh the page echo $sql="select * from users where username='".$uname."' AND password ='".$password."'"; exit; and then show what it says — Waqas Ahmad, Apr 10 '19 at 16:23
@Barmar Thank u , its a university project , so wont matter much xD — , Apr 10 '19 at 16:23
Can you comment header out then output anything to see if the conditions is really reached — Masivuye Cokile, Apr 10 '19 at 16:23
Are there any `Headers already sent` warnings in the error log? — Barmar, Apr 10 '19 at 16:23
@Moon University should be where you learn proper coding techniques, not bad habits. — Barmar, Apr 10 '19 at 16:25
Do you have earlier code that sends things like `...`? You can't output any HTML before calling `header()`. — Barmar, Apr 10 '19 at 16:30
@Barmar the html code is right below the php code in the same page — , Apr 10 '19 at 16:32
See https://stackoverflow.com/questions/845021/how-to-get-useful-error-messages-in-php for how to enable all error reporting, to make sure you're not missing any warning messages. — Barmar, Apr 10 '19 at 16:38
@Barmar No i was just testing if the `if`will execute it or no , and it did. i tried to use a debugger, it says no errors found — , Apr 10 '19 at 16:42
99% of the time the reason for `header()` failing is a "Headers already sent" error. I can't see any reason why this code wouldn't work other than that reason. — Barmar, Apr 10 '19 at 16:49
@Barmar Signin.php:1 Refused to display 'https://www.facebook.com/' in a frame because it set 'X-Frame-Options' to 'deny'. — , Apr 10 '19 at 16:50

score 1 · Answer 1 · answered Apr 10 '19 at 16:53

Try this may be it works in your case.

if(mysqli_num_rows($result)==1)
            {
              echo "<script>window.location = 'Userpanel.php';</script>";
            }
            else
            {
                echo "<script> alert('Failed to Login') </script>";   
            }

Vahe · Answer 2 · 2019-04-10T17:21:13.767

0

Remove all white space before the <?php tag, and after the ?> tag (or at least remove the ?> to automatically cause php to eliminate blank space into the html file and improper injection into the header.

See these answers for a more elaborate explanation.

PHP Header redirect not working (https://stackoverflow.com/a/24928578/1691103)

Which has a link to the following useful question answer.

How to fix "Headers already sent" error in PHP (https://stackoverflow.com/a/8028987/1691103)

Also try making sure that header name first character is uppercase, in your case header('location: Userpanel.php') should be header('Location: Userpanel.php')

edited Apr 10 '19 at 17:21

answered Apr 10 '19 at 16:27

Vahe

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Whitespace *after* the `header()` shouldn't cause a problem. – Barmar Apr 10 '19 at 16:28
I don't know if it is by mistake but the header of the script has white space. Please check against the actual source. – Vahe Apr 10 '19 at 16:32
1

@Vahe well i did remove all the white spaces , but still :/ – Apr 10 '19 at 16:37
As a final resort, try to enable errors temporarily by inserting `error_reporting(E_ALL);` above your first line of code under ` – Vahe Apr 10 '19 at 16:46
@Moon sounds like then you are not outputting content before header so make sure that the last suggestion in the answer on uppercase of `location` is applied. – Vahe Apr 10 '19 at 17:16

PHP failed to redirect after successful login

2 Answers2