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 ('b619576b6c4c249c911d82eb59784c18', -1, 1498342619, 1498342619, '36c6976c', 6, 0, 0)

Line : 172
File : sessions.php