I have my computer installed choosing the default sources server. Then today I encountered this error:
Err:10 http://cn.archive.ubuntu.com/ubuntu xenial Release Connection failed [IP: 188.8.131.52 80] ... Reading package lists... Done E: The repository 'http://cn.archive.ubuntu.com/ubuntu xenial Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. ...
The sources list is here: Ubuntu wiki
I switched several servers in the site above.
I also tried
apt clean and several methods.
However, when I followed the PackageManagerTroubleshootingProcedure, it worked well when switched to main server.
I wonder why this occurred?
BTW, the server is much faster than the main server for my network, so I prefer to the former one.