golang/go · error

unable to resolve git version: %w

Error message

unable to resolve git version: %w

What it means

Thrown by newGitRepo when gitSupportsSHA256() returns an error. That helper runs 'git version' to detect whether the installed git is new enough to support SHA-256 object format (minGitSHA256Vers). If git is not installed, not on PATH, or 'git version' output can't be parsed, this error wraps the underlying failure.

Source

Thrown at src/cmd/go/internal/modfetch/codehost/git.go:97

	unlock, err := r.mu.Lock()
	if err != nil {
		return nil, err
	}
	defer unlock()

	if _, err := os.Stat(filepath.Join(r.dir, "objects")); err != nil {
		repoSha256Hash := false
		if refs, lrErr := r.loadRefs(ctx); lrErr == nil {
			// Check any ref's hash, it doesn't matter which; they won't be mixed
			// between sha1 and sha256 for the moment.
			for _, refHash := range refs {
				repoSha256Hash = len(refHash) == (256 / 4)
				break
			}
		}
		gitSupportsSHA256, gitVersErr := gitSupportsSHA256()
		if gitVersErr != nil {
			return nil, fmt.Errorf("unable to resolve git version: %w", gitVersErr)
		}
		objFormatFlag := []string{}
		// If git is sufficiently recent to support sha256,
		// always initialize with an explicit object-format.
		if repoSha256Hash {
			// We always set --object-format=sha256 if the repo
			// we're cloning uses sha256 hashes because if the git
			// version is too old, it'll fail either way, so we
			// might as well give it one last chance.
			objFormatFlag = []string{"--object-format=sha256"}
		} else if gitSupportsSHA256 {
			objFormatFlag = []string{"--object-format=sha1"}
		}
		if _, err := Run(ctx, r.dir, "git", "init", "--bare", objFormatFlag); err != nil {
			os.RemoveAll(r.dir)
			return nil, err
		}
		// We could just say git fetch https://whatever later,

View on GitHub (pinned to b6b368adc5)

Solutions

1. Install git: 'apt-get install git' / 'apk add git' / 'yum install git'.
2. Ensure git is on PATH: 'which git && git --version'.
3. Upgrade git to at least minGitSHA256Vers if the installed version is too old to parse.
4. In containers, add 'RUN apk add --no-cache git' or equivalent.

Example fix

# before: minimal image without git
FROM alpine
RUN go build ./...
# after
FROM alpine
RUN apk add --no-cache git
RUN go build ./...

func validateGitAvailable() error {
    cmd := exec.Command("git", "--version")
    out, err := cmd.Output()
    if err != nil {
        return fmt.Errorf("git not found or not executable: %w", err)
    }
    if !strings.HasPrefix(strings.TrimSpace(string(out)), "git version") {
        return fmt.Errorf("unexpected git version output: %q", out)
    }
    return nil
}

null

null

When it happens

Trigger: Initializing a cached git repo (newGitRepo remote path) on a system where the 'git' binary is missing, too old to report a version, or returns unparseable output. The error occurs before any clone/fetch attempt.

Common situations: Minimal docker/alpine images without git installed; CI runners with git missing from PATH; git replaced by a wrapper script that doesn't emit standard version output; corrupted git installation.

Related errors

• git version extraction regexp did not match version line: %q
• failed to execute git version: %w
• globalThis.crypto is not available, polyfill required (crypt
• globalThis.performance is not available, polyfill required (
• globalThis.TextEncoder is not available, polyfill required

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/0ee6e6ce5146120b. Report an issue: GitHub.