MediaWiki sessions and cookies not working on multi-server behind CloudFlare

Question

I have a MediaWiki running on multiple AWS instances and login and registration is broken. The session.save_path is set to /tmp which is writeable and readable by anyone. I use

Answer 1

Per Aaron Schulz, don't use the default session handling, it's disastrous.

As you have memcached enabled, add

$wgMainCacheType = CACHE_ANYTHING;
$wgSessionsInObjectCache = true;

in your LocalSettings.php and let us know if things improved (they definitely should).