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 ('b247f597d626dc7ea2cc8d5ae2ff5b2f', -1, 1711616456, 1711616456, '035407ff', -4, 0, 0)

Line : 187
File : sessions.php