An error is reported when updating ubuntu. The reason is that the corresponding key has a problem.

A error occurred during the signature verification. the repository is not updated and the previous index files will be used. GPG error: http://mirrors.163.com precise-backports release: The following signatures were invalid: nodata 1 nodata 2

Sudo apt-Get clean

CD/var/lib/Apt
Sudo MV lists. Old
Sudo mkdir-P lists/partial
Sudo apt-Get clean

Sudo apt-Get update

I don't know why, but what I want to say is ..... It is best not to use the root user,:

Code:Sudo apt-Get update

From: http://blog.csdn.net/merry163/article/details/9168059