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 ('ba5b907b1df23e1387f19f0b145ec022', -1, 1506197382, 1506197382, '36e09ee8', -6, 0, 0)

Line : 187
File : sessions.php