How to tell PHP to use SameSite=None for cross-site cookies?

ini_set('session.cookie_secure', "1"); ini_set('session.cookie_httponly', "1"); ini_set('session.cookie_samesite','None'); session_start();

php 7.4 samesite in phpinfo

php 7.2 samesite does not exist in phpinfo

$currentCookieParams = session_get_cookie_params();
$cookie_domain= 'your domain';
if (PHP_VERSION_ID >= 70300) {
session_set_cookie_params([
    'lifetime' =>  $currentCookieParams["lifetime"],
    'path' => '/',
    'domain' => $cookie_domain,
    'secure' => "1",
    'httponly' => "1",
    'samesite' => 'None',
]);
} else {
session_set_cookie_params(
    $currentCookieParams["lifetime"],
    '/; samesite=None',
    $cookie_domain,
    "1",
    "1"
);
}
session_start();

Bad:

session.cookie_samesite=None

Correct:

session.cookie_samesite="None"

Explanation here

You can set the value to "None" using ini_set. There's no check that the value is supported when that function is used:

ini_set('session.cookie_samesite', 'None');
session_start();

session_set_cookie_params can also set it:

session_set_cookie_params(['samesite' => 'None']);
session_start();

The bug report for this to be supported in php.ini is here.

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As @shrimpwagon said in a comment below, session.cookie_secure must be true for this to work. PHP doesn't require it, but browsers do.