hashicorp/packer · error

Failed to create tar header for

Error message

Failed to create tar header for %s: %s

What it means

tar.FileInfoHeader failed to build a tar header from a file's metadata in Packer's compress post-processor. Even with valid stat data, the tar library can reject file metadata it cannot represent (e.g. irregular file types or unsupported mode bits), aborting archive creation.

Solutions

1. Identify the offending file from the error and check its type (stat <file>)
2. Ensure artifacts contain only regular files; remove/replace special files upstream
3. Update Packer to a version with current tar-library behavior fixes
4. Fall back to archive = "zip" if the artifact set includes non-regular files

// pre-flight: only regular files can get valid tar headers
for _, p := range artifact.Files() {
    fi, err := os.Stat(p)
    if err != nil { return err }
    if !fi.Mode().IsRegular() {
        return fmt.Errorf("%s is not a regular file (mode %s); tar cannot archive it", p, fi.Mode())
    }
}

// Go: detect header failure and fall back to zip (tolerates special files)
if err != nil && strings.Contains(err.Error(), "Error creating tar") &&
    strings.Contains(err.Error(), "Failed to create tar header") {
    cfg.Archive = "zip"
    return pp.PostProcess(ctx, ui, artifact)
}

When it happens

Trigger: createTarArchive calls tar.FileInfoHeader(fi, path) after a successful Stat and the tar package returns an error — typically for a file whose type cannot be encoded in a tar header (device files, sockets, FIFOs) or invalid metadata.

Common situations: An artifact listing a special file (socket/FIFO/device) produced by an unusual builder or plugin; very unusual file modes; Go version/library changes altering FileInfoHeader strictness.

Related errors

• Error creating tar
• Can only have 1 input file when not using tar/zip. Found
• Error creating zip
• Failed to copy data to archive
• Failed to write tar header for

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/ec90b134dd928481. Report an issue: GitHub.

Appendix: source

Thrown at post-processor/compress/post-processor.go:395

func createTarArchive(files []string, output io.WriteCloser) error {
	archive := tar.NewWriter(output)
	defer archive.Close()

	for _, path := range files {
		file, err := os.Open(path)
		if err != nil {
			return fmt.Errorf("Unable to read file %s: %s", path, err)
		}
		defer file.Close()

		fi, err := file.Stat()
		if err != nil {
			return fmt.Errorf("Unable to get fileinfo for %s: %s", path, err)
		}

		header, err := tar.FileInfoHeader(fi, path)
		if err != nil {
			return fmt.Errorf("Failed to create tar header for %s: %s", path, err)
		}

		// workaround for archive format on go >=1.10
		setHeaderFormat(header)

		if err := archive.WriteHeader(header); err != nil {
			return fmt.Errorf("Failed to write tar header for %s: %s", path, err)
		}

		if _, err := io.Copy(archive, file); err != nil {
			return fmt.Errorf("Failed to copy %s data to archive: %s", path, err)
		}
	}
	return nil
}

func createZipArchive(files []string, output io.WriteCloser) error {
	archive := zip.NewWriter(output)

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