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 ('39ac6006ad63ca02bb459ccd3a8f24c2', -1, 1417245384, 1417245384, '365159b6', 4, 0, 0)

Line : 187
File : sessions.php