phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '993947e383bc5b9db8bcbd5c7fdf6c47' 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 ('993947e383bc5b9db8bcbd5c7fdf6c47', -1, 1770138696, 1770138696, 'd849d8a2', -4, 0, 0)

Line : 187
File : sessions.php