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 ('5e3b9d0e88f53363775b9bc5334ba8b6', -1, 1398021571, 1398021571, '3651502e', 21, 0)

Line : 158
File : sessions.php