To work around this issue without making any other changes, you currently have to put the following someone in your App's bootstrap process;
$sessionStorage = new \Zend\Session\Storage\SessionStorage();
$sessionManager = new \Zend\Session\SessionManager();
I have been unable to find the exact cause and long term solution.
Failing example using skeleton https://gist.github.com/4547622
#3452 contains a fix for this.
@weierophinney Provided example still fails on develop branch (using SessionArrayStorage). On master it works fine.
zendframework/zf2#3458 addresses the exact cause of this issue and I can confirm the solution provided actually works.
Looks like casting SessionArrayStorage to array fails. SessionArrayStorage::toArray() must be used.
I can confirm that the PR attached to #3458 solves this correctly.