It looks like your session.auto_start setting is on in php.ini; that prevents OJS from properly configuring the session. I suspect if you look in your error logs you'll find warnings like this one
that make it a bit easier to debug than just working from the symptoms.
The session.auto_start variable is unusual to see enabled, so I wonder if it's been turned on for another application on your server. Depending on your server configuration, you may be able to override it using a .htaccess directive -- however, it's not possible to change that configuration option from within OJS, since PHP will already be initialized before any of that code is run.
Public Knowledge Project Team