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 ('8d4c9213cd5b53bdbad7bd6408a6e0ba', -1, 1708707708, 1708707708, '2cdc3eb7', -4, 0, 0)

Line : 187
File : sessions.php