I've gone through the duplicates here and I cannot find how to fix this problem; basically none of the core repositories update, but third-party ones do, on the whole.
For instance, I want to install the bats package, so I can see the line in sudo apt-get update:
Get:23 http://ftp.jaist.ac.jp/pub/Linux/ubuntu xenial/universe amd64 Packages [7,532 kB]
I presume this is OK, even though at the end I get:
E: Failed to fetch http://ftp.jaist.ac.jp/pub/Linux/ubuntu/dists/xenial/main/binary-arm64/Packages
404 Not Found
And also for xenial-updates and xenial-security, but the text says "They have been ignored, or old ones used instead." Note that the main site and random mirrors all fail.
Now, apt list *bats* reports merely libatspi2.0-0.
Third-party repositories (Opera and ROS, for instance) work fine, but what could be causing my problem with the official repositories? I'm also not getting any updates from there.
Note that when I work with Docker, Dockerfile RUN apt-get works as expected, so it's probably not some network or quota issue.
arm64? I don't think that mirror has any arm64 files. – muru Nov 19 '18 at 08:52arm64, so that's why I said I don't think it's a problem. – Ken Y-N Nov 19 '18 at 08:55