In MediaWiki 1.27.1 (our production release) and 1.28 (our testing release), I fail to setup a multi-domain shared session with the method explained in Manual:Shared_database#Sharing_sessions. (Without CentralAuth.)

To replicate the issue you have to:

1. Have an account for https://en.wikitolearn.org
2. Login into https://en.wikitolearn.org without the "remember me" checkbox selected
3. Go to https://it.wikitolearn.org

you will be logged out from both domains.

I tried to have different sessions for each domain (now is online this version) with the

$wgSessionName = $wgCookiePrefix . "session_" . $wiki;

Where $wiki is the current wiki subdomain but the issue is the same, i think is because the user id and username cookie

I suppose this feature is broken with the 1.27 release ( * Massive overhaul to session handling )

If there is a working example that I can look at I please show me.

This is our config file