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 ('5ea3e02610a1a87eca46bfc8a5f3335b', -1, 1540033323, 1540033323, '36c637a7', 4, 0, 0)

Line : 189
File : sessions.php