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 ('2c8feb8e4ef4daf08a7b1e0e3bb8baf8', -1, 1558489461, 1558489461, '035793b8', 14, 0, 0)

Line : 187
File : sessions.php