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 ('6dff0ee7f20bc1c1e8d8b5b0f654ad2b', -1, 1711648976, 1711648976, '12e8bc7a', -10, 0, 0)

Line : 187
File : sessions.php