PHP - setcookie(); not working - php

Question

I've made a login, that sets a cookie with a value of the imputed email address, so in the global.php file, it stores an array of the users data using:
$email = $_COOKIE["PeopleHub"];
$getuserdata = mysqli_query($con, "SELECT * FROM Earth WHERE email='$email'");
$userdata = mysqli_fetch_array($getuserdata, MYSQLI_ASSOC);
The cookie isn't being set, I know this because I made a test file:
echo $_COOKIE["PeopleHub"];
It just made a blank page.
The login code (where the cookie is set):
<?php
include "global.php";
?>
<h2>Login</h2>
<?php
echo "We currently have <b>" . $usercount . "</b> members, <b>" . $onlinecount . "</b> of which are online. ";
?>
<br>
<br>
<?php
if(isset($_POST["email"])){
$email = $_POST["email"];
$password = sha1($_POST["password"]);
$check = mysqli_query($con, "SELECT * FROM Earth WHERE `email`='$email' AND `password`='$password'");
$check = mysqli_num_rows($check);
if($check == 1){
setcookie("PeopleHub", $email, 0, '/');
echo "We logged you in!";
}
else {
echo "We couldn't log you in!";
}
}
?>
<form action="<?php echo $_SERVER['REQUEST_URI']; ?>" method="post">
Email <input name="email" placeholder="Email Address" required="" type="text"><br>
Password <input name="password" placeholder="Password" required="" type="password"><br>
<input type="reset" value="Start Over">
<input type="submit" value="Login">
</form>

Answer 1

You have to set cookies before any headers are sent out.
From the manual:
setcookie() defines a cookie to be sent along with the rest of the HTTP headers. Like other headers, cookies must be sent before any output from your script (this is a protocol restriction). This requires that you place calls to this function prior to any output, including and tags as well as any whitespace.
This means you will need to look into output buffering if you wish to use this code as is.
<?php
ob_start();
echo "Hello\n";
setcookie("cookiename", "cookiedata");
ob_end_flush();
?>
Depending on the contents of global.php, this might work for you. All I did was remove any output before setcookie() is called. If global.php contains any whitespace or HTML output in it this won't work:
<?php
include "global.php";
if(isset($_POST["email"])){
$email = $_POST["email"];
$password = sha1($_POST["password"]);
$check = mysqli_query($con, "SELECT * FROM Earth WHERE `email`='$email' AND `password`='$password'");
$check = mysqli_num_rows($check);
if($check == 1){
setcookie("PeopleHub", $email, 0, '/');
echo "We logged you in!";
}
else {
echo "We couldn't log you in!";
}
}
?>
<h2>Login</h2>
<?php
echo "We currently have <b>" . $usercount . "</b> members, <b>" . $onlinecount . "</b> of which are online. ";
?>
<br>
<br>
<form action="<?php echo $_SERVER['REQUEST_URI']; ?>" method="post">
Email <input name="email" placeholder="Email Address" required="" type="text"><br>
Password <input name="password" placeholder="Password" required="" type="password"><br>
<input type="reset" value="Start Over">
<input type="submit" value="Login">
</form>

Answer 2

Just wanted to point out, I had an issue with setcookie not working. When I investigated the file further it was encoded as UTF-8 with BOM. When I re-encoded it as UTF-8 without BOM setcookie worked fine, so the BOM was being written before my first php tag was encountered. I guess enabling buffering in my php.ini file probably would fix this too.
Someone may eventually find this information helpful.

Answer 3

I had the same problem and it turned out that it was caused because the domain I was passing to the function had a custom port (which is not allowed).

Answer 4

I had another problem with cookie update using setcookie function.
So I've set cookie string made from array using php serialize function. From now on I was not able to update that cookie - setcookie function was simply not working, wheather is was setting serialized string or any other simple string.
Then I've set another cookie with new cookie key, this time data was encoded with json_encode function. This time I was able to set the cookie and update it :-)

Answer 5

Mine was a slightly more exotic case: turns out my ad blocker (I use 1Blocker) kills cookies with certain names. In my case it was a cookie name ending with _login. I changed the name and it started working.

Answer 6

Just wanted to add that setcookie was not working for me when the user utilized my website with an url like this: https://mywebsite89898989.com. But when the website url was changed to https://www.mywebsite89898989.com setcookie worked correctly.
I am about as far from an expert as one can be so perhaps someone more knowledgeable can explain this behavior.
I just note this information to hopefully save someone some time debugging...

Answer 7

If you are using XAMPP you may find this helpful: Today I was trying to find the reason for a cookie bug. On my local XAMPP server setcookie() was working fine, but once I uploaded the project to my webhosting it simply stopped working, the cookie was not set. XAMPP uses PHP v8.1.10 and webhosting uses PHP v8.1.16, so version differences are not the cause of the bug.
It turned out my mistake was to output some text before setcookie() was called (so HTTP headers were already sent), but I have no idea why it was working on localhost/XAMPP. It really shouldn't be like that.