When cross-compiling a snap on (for example) amd64 to run on armhf, I have rules like this in the snapcraft.yaml: stage-packages: - on amd64 to armhf: - "sqlite3:armhf" - else: - "sqlite3" Because when running the snap on an armhf machine, obviously it needs the armhf version and not the amd64 version. Hence the "sqlite:armhf" syntax to specify using the armhf version of the package. However, snapcraft cleanbuild doesn't setup the container in a way that supports this as it fails with: Failed to fetch stage packages: Error downloading packages for part 'gg-sdk-deps': The package 'sqlite3:armhf' was not found. You may need to add support for this architecture with 'dpkg --add-architecture armhf'.. Which obviously I can't do inside the lxd container as it was launched/setup by snapcraft with something like `snapcraft cleanbuild --target-arch=armhf`. So I think the bug here is that specifying `--target-arch=SOME_OTHER_ARCH` and arguably some permutation of the `architectures` key setup inside snapcraft.yaml need to trigger snapcraft to do the necessary things inside the container to setup installing cross-architecture packages, i.e. the dpkg --add-architecture step suggested and also setup /etc/apt/sources.list.