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 ('6a4a54e2bc93e73cba8ef28eb4ee7926', -1, 1553346797, 1553346797, '365acce9', -4, 0, 0)

Line : 187
File : sessions.php