How to fix a "Failed to fetch binary-armhf/Packages" error during apt-get update?

When I run sudo apt-get update I get the following error:

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/trusty/main/binary-armhf/Packages  404  Not Found [IP: 91.189.91.15 80]

E: Some index files failed to download. They have been ignored, or old ones used instead.

I've tried looking in /etc/apt/sources.list.d/ to see if anything in that directory can be removed but all that is in there is

nodesource.list
nodesource.list.save

In my sources.list file I have:

deb http://ports.ubuntu.com/ubuntu-ports/ trusty main
deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty main
deb http://ports.ubuntu.com/ubuntu-ports/ trusty-updates main
deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-updates main
deb http://ports.ubuntu.com/ubuntu-ports/ trusty-security main
deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-security main
deb http://archive.ubuntu.com/ubuntu trusty main
# deb-src http://archive.ubuntu.com/ubuntu trusty main

Can anyone recommend a way of fixing this error?

You might install the armhf cross tools which add armhf as foreign architecture (your architecture maybe i386 or amd64). You can launch this command to verify:

dpkg --print-foreign-architectures

If the output includes armhf, you can simply remove it by running the command:

sudo dpkg --remove-architecture armhf

Finally, launch your sudo apt-get update again.

The offending line was from the x86 source list. Removing it eliminated the error. The following is the correct list for armf architecture.

deb http://ports.ubuntu.com/ubuntu-ports/ trusty main
deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty main
deb http://ports.ubuntu.com/ubuntu-ports/ trusty-updates main
deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-updates main
deb http://ports.ubuntu.com/ubuntu-ports/ trusty-security main
deb-src http://ports.ubuntu.com/ubuntu-ports/ trusty-security main