phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'phpbb_sessions.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 ('8a79b02d9c22c5c3c953b9a5161f6695', -1, 1768185866, 1768185866, 'd849d897', 4, 0, 0)

Line : 187
File : sessions.php