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 ('b8f586eae202e5e03f59119f8e0935b3', -1, 1506307335, 1506307335, '369015c3', -9, 0, 0)

Line : 187
File : sessions.php