phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('a3527ce91db6c81ce2cfae9661f73dd7', -1, 1397854353, 1397854353, '36c6e079', 4, 0)

Line : 158
File : sessions.php