phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '876b846db7e9996d720aed6a65c7f28b' for key 'phpbb_sessions.PRIMARY'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('876b846db7e9996d720aed6a65c7f28b', -1, 1771104400, 1771104400, 'd849d800', -4, 0, 0)

Line : 187
File : sessions.php