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 ('d6ae0627fb2ee49ff31d4e6459566fcf', -1, 1529617696, 1529617696, '36c42a92', 54, 0, 0)

Line : 187
File : sessions.php