phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('bcd35b23f1f3273e507b6dbfa0b6ea77', -1, 1417245728, 1417245728, '365159b6', 6, 0, 0)

Line : 187
File : sessions.php