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 ('874e4874410294bcec2a5c63a3806f2c', -1, 1561042868, 1561042868, '365b476c', 18, 0, 0)

Line : 187
File : sessions.php