I'm trying to build a package with snapcraft cleanbuild which uses lxd to build a snap in a container. Unfortunately it fails pretty quickly with an http 500 error. The host is able to connect fine, and in fact the url the error message prints is actually a 404, not 500. So I don't understand where the 500 comes from.
$ snapcraft cleanbuild
"confinement" property not specified: defaulting to "strict"
Creating snapcraft-unyieldingly-multiciliated-vita
Starting snapcraft-unyieldingly-multiciliated-vita
Setting up container with project assets
./
./audacity
./snapcraft.yaml
Waiting for a network connection...
Network connection established
Hit:1 http://archive.ubuntu.com/ubuntu xenial InRelease
Get:2 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [94.5 kB]
Get:3 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB]
Get:4 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages [213 kB]
Ign:5 http://archive.ubuntu.com/ubuntu xenial-updates/main Translation-en
Ign:6 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
Ign:7 http://archive.ubuntu.com/ubuntu xenial-updates/universe Translation-en
Ign:5 http://archive.ubuntu.com/ubuntu xenial-updates/main Translation-en
Ign:6 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
Ign:7 http://archive.ubuntu.com/ubuntu xenial-updates/universe Translation-en
Ign:5 http://archive.ubuntu.com/ubuntu xenial-updates/main Translation-en
Ign:6 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
Ign:7 http://archive.ubuntu.com/ubuntu xenial-updates/universe Translation-en
Err:5 http://archive.ubuntu.com/ubuntu xenial-updates/main Translation-en
500 Internal Server Error
Ign:6 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
Ign:7 http://archive.ubuntu.com/ubuntu xenial-updates/universe Translation-en
Fetched 402 kB in 0s (648 kB/s)
Reading package lists... Done
E: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/xenial-updates/main/i18n/Translation-en 500 Internal Server Error
E: Some index files failed to download. They have been ignored, or old ones used instead.
Command '['lxc', 'exec', 'snapcraft-unyieldingly-multiciliated-vita',
'--', 'apt-get', 'update']' returned non-zero exit status 100