phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('5c078f052616fec24d7449963f5d9739', -1, 1513292112, 1513292112, '3652519a', 5, 0, 0)

Line : 189
File : sessions.php