The following taps are not trusted: bats-core/bats-core Homebrew will ignore formulae, casks and commands from these taps when `HOMEBREW_REQUIRE_TAP_TRUST` is set. This will become the default in Homebrew 6.0.0 or 5.2.0, whichever comes first. Enable trust checks now with: export HOMEBREW_REQUIRE_TAP_TRUST=1 Trust specific formulae, casks or commands with: brew trust --formula <user>/<tap>/<formula> brew trust --cask <user>/<tap>/<cask> brew trust --command <user>/<tap>/<command> or trust installed formulae from these taps with: brew trust --formula bats-core/bats-core/bats-assert bats-core/bats-core/bats-file bats-core/bats-core/bats-support You can trust all formulae, casks and commands from these taps with: brew trust bats-core/bats-core Prefer trusting only the specific formulae, casks or commands you need. Untap them with: brew untap bats-core/bats-core To keep allowing them by default during the transition: export HOMEBREW_NO_REQUIRE_TAP_TRUST=1 This is not recommended and will be removed in a later release.