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 ('b1afcd7f606d794ea6902d93df0c1d28', -1, 1728096049, 1728096049, '2cdcfbec', -7, 0, 0)

Line : 172
File : sessions.php