Also seeing this in the apache error log:
[Tue Feb 17 12:34:58.892291 2015] [:error] [pid 2452] [client x.x.x.x:52802] PHP Fatal error: Call to undefined method rcube_template::nocacheing_headers() in /usr/share/roundcubemail/index.php on line 46
[Tue Feb 17 12:34:58.893049 2015] [:error] [pid 2452] [client x.x.x.x:52802] MDB2 Error: constraint violation (-3): _doQuery: [Error message: Could not execute statement]\n[Last executed query: INSERT INTO session (sess_id, vars, ip, created, changed) VALUES ('j94839sgr9nqmaqjr30huteq86', 'dGVtcHxiOjE7bGFuZ3VhZ2V8czo1OiJlbl9VUyI7dGFza3xzOjU6ImxvZ2luIjs=', 'x.x.x.x', '2015-02-17 12:34:58', '2015-02-17 12:34:58')]\n[Native code: 1062]\n[Native message: Duplicate entry 'j94839sgr9nqmaqjr30huteq86' for key 'PRIMARY']\n