GoGitActionCache failed to get commit %s with sha %s subpath

Error message

GoGitActionCache failed to get commit %s with sha %s subpath '%s' at %s: %w

What it means

GetTarArchive looks up the fetched commit with gogitrepo.CommitObject(plumbing.NewHash(sha)). This error wraps failure to load that commit object: the sha is not a 40-hex string (NewHash truncates/garbles it), the object is missing from the shallow clone (depth=1 fetched a different commit), or the object database is corrupt.

Source

Thrown at pkg/runner/action_cache.go:143

// Sys implements fs.FileInfo.
func (g *GitFileInfo) Sys() any {
	return nil
}

func (c GoGitActionCache) GetTarArchive(ctx context.Context, cacheDir, sha, includePrefix string) (io.ReadCloser, error) {
	logger := common.Logger(ctx)

	gitPath := path.Join(c.Path, safeFilename(cacheDir)+".git")

	logger.Infof("GoGitActionCache get content %s with sha %s subpath '%s' at %s", cacheDir, sha, includePrefix, gitPath)

	gogitrepo, err := git.PlainOpen(gitPath)
	if err != nil {
		return nil, fmt.Errorf("GoGitActionCache failed to open bare git %s with sha %s subpath '%s' at %s: %w", cacheDir, sha, includePrefix, gitPath, err)
	}
	commit, err := gogitrepo.CommitObject(plumbing.NewHash(sha))
	if err != nil {
		return nil, fmt.Errorf("GoGitActionCache failed to get commit %s with sha %s subpath '%s' at %s: %w", cacheDir, sha, includePrefix, gitPath, err)
	}
	t, err := commit.Tree()
	if err != nil {
		return nil, fmt.Errorf("GoGitActionCache failed to open git tree %s with sha %s subpath '%s' at %s: %w", cacheDir, sha, includePrefix, gitPath, err)
	}
	files, err := commit.Files()
	if err != nil {
		return nil, fmt.Errorf("GoGitActionCache failed to list files %s with sha %s subpath '%s' at %s: %w", cacheDir, sha, includePrefix, gitPath, err)
	}
	rpipe, wpipe := io.Pipe()
	// Interrupt io.Copy using ctx
	ch := make(chan int, 1)
	go func() {
		select {
		case <-ctx.Done():
			wpipe.CloseWithError(ctx.Err())
		case <-ch:
		}

View on GitHub (pinned to 4f41128141)

Solutions

Clear the affected cache repo: rm -rf <gitPath from the error>, then re-run so Fetch re-fetches a consistent sha.
Pin 'uses:' to an immutable tag or full sha so the fetched commit matches the requested one.
Re-run — if a force-push raced the fetch, a fresh run re-resolves the ref.
Avoid sharing one cache dir across concurrently running act instances.

Example fix

# before
uses: org/repo/.github/actions/build@main   # ref moved between runs

# after
uses: org/repo/.github/actions/build@v3.1.0

Defensive patterns

Strategy: fallback

Validate before calling

git --git-dir="$HOME/.cache/act/<cache-name>.git" cat-file -t <sha> 2>/dev/null || echo 'commit not in cache — clear it'

Prevention

Pin reusable actions to immutable tags/shas.
Clear the affected *.git cache after force-pushes upstream.
Re-run the job when refs move mid-run.

When it happens

Trigger: The sha passed in does not correspond to what Fetch actually stored — e.g. the ref moved between fetch and materialize, a shallow (Depth:1) fetch did not include the requested commit, or cache corruption dropped the object.

Common situations: Branch force-pushed mid-run; action ref updated between two act runs sharing a cache; corrupt cache after an interrupted run; invalid sha characters in 'uses: repo@<ref>'.

Related errors

AI-assisted analysis of nektos/act@4f41128141 (2026-08-15). Data as JSON: /api/errors/f6db8febddb48d22. Report an issue: GitHub.