phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('f339f5d9b4d53ade6196c9f076ddf92e', -1, 1550693661, 1550693661, '36c518ce', 2, 0, 0)

Line : 187
File : sessions.php