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, session_admin) VALUES ('7363ca969bf411c1881ca7b6a510aeed', -1, 1397674623, 1397674623, '6ca2d4f2', 44, 0, 0)

Line : 187
File : sessions.php