phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'd6b939756f8d1e840d8c9f1249f05f5b' 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 ('d6b939756f8d1e840d8c9f1249f05f5b', -1, 1770091882, 1770091882, 'd849d8a2', -4, 0, 0)

Line : 187
File : sessions.php