Не удается устранить ошибку BADSIG - 12.04

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Какой самый простой способ устранить ошибки apt-get BADSIG GPG?

Я пытаюсь исправить ошибку BADSIG, но она не изменится.

Это ошибка.

Reading package lists... Done
W: GPG error: http://au.archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]>
W: GPG error: http://au.archive.ubuntu.com precise-updates Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]>
W: GPG error: http://au.archive.ubuntu.com precise-backports Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]>
W: GPG error: http://extras.ubuntu.com precise Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <[email protected]>
W: GPG error: http://security.ubuntu.com precise-security Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]>

Я попытался обновить его.

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 40976EAF437D05B5

Но это не меняется.

gpg: requesting key 437D05B5 from hkp server keyserver.ubuntu.com
gpg: key 437D05B5: "Ubuntu Archive Automatic Signing Key <[email protected]>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1
sayth@sayth-TravelMate-5740G:~$