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 ('2e1e3040579ceb0a8e59e5bf2aa464c3', -1, 1513622035, 1513622035, '3652385f', -4, 0, 0)

Line : 193
File : sessions.php