apt looking for i386 files, even though architecture is amd64

Question

I am trying to use a file repository for updating linux/ubuntu on a non-connected machine. The architecture for this machine (uname -a):

x86_64 GNU/Linux

The results of dpkg --printarchitecture are:

amd64

It is a Trusty Tahr amd64 machine, and it specifically says this, for example, in the aptitude sources.list file. Also, the "About this Computer" in ubuntu specifically says the machine is 64-bit. So, I installed the amd64 packages on the machine. However, when I try to do apt-get update, I get errors such as:

W: Failed to fetch file:/var/spool/apt-mirror-trusty/mirror/archive.ubuntu.com/ubuntu/dists/trusty/main/binary-i386/Packages  File not found

So, in other words, even though it is a 64-bit machine, apt is inexplicably trying to read i386 packages. Why is it doing this and how can I make it use the 64-bit packages?

Note that there is nothing in sources.list that specifies i386.

The only uncommented line in the sources.list file is:

deb file:///var/spool/apt-mirror-trusty/mirror/archive.ubuntu.com/ubuntu trusty main restricted universe multiverse

Answer 1

On Ubuntu amd64 installations, i386 is enabled as an additional architecture by default. apt & co. expect repositories to provide all configured architectures, which causes the error you're seeing.

Since your mirror only has amd64 packages, you should mark it as such:

deb [ arch=amd64 ] file:///var/spool/apt-mirror-trusty/mirror/archive.ubuntu.com/ubuntu trusty main restricted universe multiverse