Installation fails on macOS with recent Homebrew changes

Homebrew 6.0.0 was released few hours ago, but even after upgrading Homebrew, we still get this error message:

Error: Refusing to load formula coverallsapp/coveralls/coveralls from untrusted tap coverallsapp/coveralls.
Run `brew trust --formula coverallsapp/coveralls/coveralls` or `brew trust coverallsapp/coveralls` to trust it.
Failed to install coveralls via Homebrew (macOS).
Error: Process completed with exit code 1.

@mtl1979

Thanks, @mtl1979. We'll check it out.

What happened

Homebrew 6.0.0 (released today, June 11) made a breaking security change: third-party taps are no longer loaded until the user explicitly trusts them, because a tap is arbitrary unsandboxed Ruby that runs with user privileges. Official Homebrew taps stay trusted by default; everything else — including coverallsapp/coveralls — now refuses to load until trusted. There is nothing wrong with the tap, but nothing the tap itself can do to mark itself trusted (that would defeat the purpose). Trust is granted on the client, in one of three ways:

brew install <user/repo/formula> — a fully-qualified install auto-trusts just that formula
brew trust --formula <user/repo/formula> — trust one formula
brew trust <user/repo> — trust the whole tap

The fix

We will fix this in the Coveralls GitHub Action (this repo) asap since it is the "client" in this scenario, automatically installing the Coveralls Homebrew Formula when it recognizes CI runners running macos.

Until that's ready, here is a workaround:

Workaround

Immediate workaround for users with issue #264
Users who can't wait for the new release of the Coveralls GitHub Action (or who pin exact versions) can add one step before the action in their workflow:

- name: Trust Coveralls Homebrew tap (Homebrew 6 requirement)
  if: runner.os == 'macOS'
  run: brew trust coverallsapp/coveralls
- uses: coverallsapp/github-action@v2

Open PR for fix here:
#265

Make coveralls tap trusted in gh actions

[ci] Trust Coveralls Homebrew tap

Work around coverallsapp/github-action#264

ci: trust coveralls homebrew tap on macOS

chore: add Jira automation workflows (#135)

Any plans to merge it?

Fixed in v2.3.8: if you use coverallsapp/github-action@v2, you'll pick it up automatically on your next CI run, no workflow changes needed.

Cause: Homebrew 6.0.0 introduced a tap trust requirement: formulae from third-party taps refuse to load until trusted. The action now installs via the fully-qualified formula name (brew install coverallsapp/coveralls/coveralls), which trusts the formula automatically and works on both old and new Homebrew (#265).

Verified end-to-end on current macos-latest (macOS 26) and macos-15 images using the published @v2 tag: smoke test run — Homebrew 6 trust enforcement active, formula auto-trusted, bottle poured, coverage report uploaded successfully.

If you pin an exact version or SHA, either bump to v2.3.8 or add this step before the action:

- name: Trust Coveralls Homebrew tap (Homebrew 6 requirement)
  if: runner.os == 'macOS'
  run: brew trust coverallsapp/coveralls

Thanks for the report and your patience!

Add cross-platform smoke test for the published action (#267)

Fix macOS install for Homebrew 6.0.0 tap trust requirement (coveralls…

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Installation fails on macOS with recent Homebrew changes #264

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Installation fails on macOS with recent Homebrew changes #264

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afinetooth commented on Jun 11, 2026

afinetooth commented on Jun 11, 2026

What happened

The fix

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afinetooth commented on Jun 11, 2026

Giorgi commented on Jul 25, 2026

afinetooth commented on Jul 27, 2026

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