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 ('71b838a3f7c2519ab2759765b2d2e87f', -1, 1506313476, 1506313476, '36e0d65d', 3, 0, 0)

Line : 187
File : sessions.php