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 ('cd6e9069fbb8278b33b3bc8ea8c7cfdd', -1, 1728478268, 1728478268, '03ee524d', -7, 0, 0)

Line : 172
File : sessions.php