Ubuntu update 报key错误

安装了一个Ubuntu 12.04 beta1版本。

当我

apt-get update

报一个错误

W: GPG error: http://security.ubuntu.com precise-security Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key

我更换源，也不行，改成国外的也是一样。

sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update

这样就搞定了。

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[ubuntu进行apt-get时候出现Package ssh is not available, but is referred to by another package 错误

->

apt-get update

]