phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb_real_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('601f6c0e9638fc9c40754258c507feba', -1, 1436228563, 1436228563, '36e011b2', 6, 0)

Line : 158
File : /var/www/vhosts/pravniki.info/httpdocs/includes/sessions.php