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 ('42f5b3f9b68becbc6a2d8e86c7f0bdf8', -1, 1711718711, 1711718711, '369c30c0', 7, 0, 0)

Line : 187
File : sessions.php