PHP SameSite session problem, session doesn't work

Question

I hope anybody can give me some ideas to my problem. I am trying to apply SameSite cookie to make session work but it seems it doesn't work. The visited site html:

<iframe src="https://www.example.com/test/iframe.php"></iframe>

Iframe source site:

    <?php
    header('Set-Cookie: cross-site-cookie=PHPSESSID; SameSite=None; Secure');
    session_start();
    if(!isset($_SESSION['test'])){
        echo 1;
        $_SESSION['test'] = 'ee2';
    }else{
        echo $_SESSION['test'];
    }

If I visit the website, I still receive A cookie associated with a cross-site resource at https://www.example.com/ was set without the SameSite attribute. It has been blocked, as Chrome now only delivers cookies with cross-site requests if they are set with SameSite=None and Secure. message in browser console and session is not saved.

Strange thing is that the cookie has been actually set:

Am I missing something? Why do I get this message in console if cross-site-cookie is set and what could be reasons for session to not work? I am using php 7.1.33. If I open iframe directly, it works and it also works properly if I open the site with browser where I haven't enabled the SameSite by default cookies flag for testing.

Answer 1

I resolved it by editing .htaccess

<ifmodule mod_headers.c>
Header always edit Set-Cookie ^(.*)$ $1;SameSite=None;Secure
</ifmodule>