phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('f6c91f47dc38acb1d989df4c7bb9d378', -1, 1771772608, 1771772608, '54ccfc03', -6, 0, 0)

Line : 187
File : sessions.php