Ubuntu not updating, Some index files failed to download, how?

Question

ubuntu

Somehow my server got out of control, I try to update, I get
W: Failed to fetch archive.ubuntu.com/ubuntu/dists/trusty-backports/u... 404 Not Found
W: Failed to fetch archive.ubuntu.com /ubuntu/dists/trusty-backports/m... 404 Not Foun
E: Some index files failed to download. They have been ignored, or old ones used instead.
cat /etc/issue
Ubuntu 14.04.3 LTS \n \l
who faced? I look at the options on the network, but not one is suitable ....

Answer 1

It turned out that the provider blocks ubunt updates via http did an update via ftp, everything was fixed .... The server was moved to another dc, and things are like that there ...

Answer 2

sudo rm /var/lib/apt/lists/* -vf
sudo apt-get update

Answer 3

Here is a bug report on a similar topic: https://bugs.launchpad.net/ubuntu/+source/apt/+bug...
They say that changing the mirror helps.