wagoodman/dive · error

cannot marshal export payload: %w

Error message

cannot marshal export payload: %w

What it means

Returned by ExportTo when building the JSON export payload via export.NewExport(analysis).Marshal() fails. The analysis object is converted to an export structure and serialized; marshalling only fails if the payload contains values Go's json encoder cannot represent — most notably NaN/Inf float fields (efficiency or size ratios) produced by degenerate analyses such as zero-byte images.

Source

Thrown at cmd/dive/cli/internal/command/adapter/exporter.go:47

func (e *jsonExporter) ExportTo(ctx context.Context, analysis *image.Analysis, path string) error {
	log.WithFields("path", path).Infof("exporting analysis")

	mon := bus.StartTask(payload.GenericTask{
		Title: payload.Title{
			Default:      "Exporting details",
			WhileRunning: "Exporting details",
			OnSuccess:    "Exported details",
		},
		HideOnSuccess:      false,
		HideStageOnSuccess: false,
		ID:                 analysis.Image,
		Context:            fmt.Sprintf("[file: %s]", path),
	})

	bytes, err := export.NewExport(analysis).Marshal()
	if err != nil {
		mon.SetError(err)
		return fmt.Errorf("cannot marshal export payload: %w", err)
	} else {
		mon.SetCompleted()
	}

	file, err := e.filesystem.OpenFile(path, os.O_RDWR|os.O_CREATE, 0644)
	if err != nil {
		return fmt.Errorf("cannot open export file: %w", err)
	}
	defer file.Close()

	_, err = file.Write(bytes)
	if err != nil {
		return fmt.Errorf("cannot write to export file: %w", err)
	}
	return nil
}

View on GitHub (pinned to d6c691947f)

Solutions

1. Verify the image is a real, non-empty image (docker save and check size); try a known-good image like alpine to confirm the export path works
2. Upgrade dive — NaN-guarding in the export marshalling has been addressed in newer versions
3. If it reproduces, capture the analysis (run without --json) and report the image manifest details upstream
4. As a workaround for CI, drop --json and rely on the text/CI output until fixed

// reject degenerate images before exporting
if analysis.SizeBytes == 0 {
    return fmt.Errorf("cannot export zero-byte image analysis")
}

if err := exporter.ExportTo(ctx, analysis, path); err != nil {
    if strings.Contains(err.Error(), "cannot marshal export payload") {
        // payload problem (often NaN metrics): report image details upstream,
        // fall back to human-readable CI output
    }
    return err
}

When it happens

Trigger: Running dive with --json <path> (export.jsonPath set) on an analysis whose computed metrics include NaN or +Inf — e.g. an image with zero total bytes or zero reference bytes, making an efficiency ratio 0/0.

Common situations: Exporting a tiny FROM scratch image that only COPYs an empty file, or a synthetic/test image with no file content; also possible after an analyzer change introduces an uninitialized metric field.

Related errors

• cannot open export file: %w
• cannot write to export file: %w
• cannot export analysis: %w
• directory for JSON export does not exist: %s
• failed to unmarshal docker config: %w

AI-assisted analysis of wagoodman/dive@d6c691947f (2026-08-15). Data as JSON: /api/errors/377cecbea282074b. Report an issue: GitHub.