apt-get update is failed on
arch: arm64 and
dist: xenial environment by following error.
It is related to the mongodb repository issue. It is trying to get mongodb binary repository for amd64, not arm64, seeing the log.
$ tool/travis_retry.sh sudo apt-get update -yq + sudo apt-get update -yq ... W: GPG error: https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/4.0 Release: The following signatures were invalid: BADSIG 68818C72E52529D4 MongoDB 4.0 Release Signing Key <firstname.lastname@example.org> W: The repository 'https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/4.0 Release' is not signed. E: Failed to fetch https://repo.mongodb.org/apt/ubuntu/dists/xenial/mongodb-org/4.0/multiverse/binary-amd64/Packages Writing more data than expected (296872 > 286809) ...