hashicorp/packer · error

Failed to generate a fingerprint: %s

Error message

Failed to generate a fingerprint: %s

What it means

Returned by Version.Initialize when generating a new ULID fingerprint for a version fails. The fingerprint uniquely identifies a version's content in HCP Packer; without it, a new version cannot be initialized.

Source

Thrown at internal/hcp/registry/types.version.go:61

}

// Initialize prepares the version to be used with HCP Packer.
func (version *Version) Initialize() error {
	if version == nil {
		return errors.New("Unexpected call to initialize for a nil Version")
	}

	// Bydefault we try to load a Fingerprint from the environment variable.
	// If no variable is defined we generate a new fingerprint.
	version.Fingerprint = os.Getenv(env.HCPPackerBuildFingerprint)

	if version.Fingerprint != "" {
		return nil
	}

	fp, err := ulid.New(ulid.Now(), ulid.Monotonic(rand.New(rand.NewSource(time.Now().UnixNano())), 0))
	if err != nil {
		return fmt.Errorf("Failed to generate a fingerprint: %s", err)
	}
	version.Fingerprint = fp.String()

	return nil
}

// StoreBuild stores a build for buildName to an active version.
func (version *Version) StoreBuild(buildName string, build *Build) {
	version.builds.Store(buildName, build)
}

// Build gets the store build associated with buildName in the active version.
func (version *Version) Build(buildName string) (*Build, error) {
	build, ok := version.builds.Load(buildName)
	if !ok {
		return nil, errors.New("no associated build found for the name " + buildName)
	}

View on GitHub (pinned to eb36e3c3e4)

Solutions

1. Re-run Packer; the failure is tied to random source state at init time
2. Check system entropy source (/dev/urandom) and clock sanity if it reproduces
3. Report a bug if reproducible — the ulid monotonic reader should never fail here under normal conditions

if err := version.Initialize(); err != nil && strings.Contains(err.Error(), "Failed to generate a fingerprint") {
    // rare ULID failure: simply retry initialization
    err = version.Initialize()
}

When it happens

Trigger: version.Fingerprint is empty and ulid.New(ulid.Now(), ulid.Monotonic(rand.New(rand.NewSource(time.Now().UnixNano())), 0)) returns an error — essentially only on ULID entropy/monotonic-reader failure.

Common situations: Extremely rare; effectively only seen if the system clock/entropy environment is broken. In practice this branch is nearly unreachable on healthy systems.

Related errors

• The version associated to the fingerprint %v is complete. If
• error retrieving version from HCP Packer Registry: %s
• error retrieving channel from HCP Packer Registry: %s
• there is no version associated with the channel %s
• the version %s is revoked and can not be used on Packer buil

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/47f02233e1f98b61. Report an issue: GitHub.