GoogleContainerTools/skaffold · error

marshalling configuration: %w

Error message

marshalling configuration: %w

What it means

Wraps a yaml.MarshalWithSeparator failure in `skaffold diagnose` when serializing the parsed skaffold configs for the diagnostics output. Marshalling a parsed latest.SkaffoldConfig should virtually never fail; if it does, the config contains data that cannot round-trip through the YAML encoder (unsupported types introduced by a schema/plugin mismatch).

Source

Thrown at cmd/skaffold/app/cmd/diagnose.go:98

	}

	if !yamlOnly {
		if err := printArtifactDiagnostics(ctx, out, configs); err != nil {
			return err
		}
	}
	// remove the dependency config references since they have already been imported and will be marshalled together.
	for i := range configs {
		configs[i].(*latest.SkaffoldConfig).Dependencies = nil
	}
	if enableTemplating {
		if err := tags.ApplyTemplates(configs); err != nil {
			return err
		}
	}
	buf, err := yaml.MarshalWithSeparator(configs)
	if err != nil {
		return fmt.Errorf("marshalling configuration: %w", err)
	}

	out.Write(buf)

	return nil
}

func printArtifactDiagnostics(ctx context.Context, out io.Writer, configs []schemaUtil.VersionedConfig) error {
	runCtx, err := getRunContext(ctx, opts, configs)
	if err != nil {
		return fmt.Errorf("getting run context: %w", err)
	}
	tagger, err := tag.NewTaggerMux(runCtx)
	if err != nil {
		return fmt.Errorf("getting tagger: %w", err)
	}
	imageTags, err := deployutil.ImageTags(ctx, runCtx, tagger, out, runCtx.Artifacts())
	if err != nil {

View on GitHub (pinned to a1189de023)

Solutions

1. Re-run with an official skaffold build matching your skaffold.yaml apiVersion
2. Remove custom transforms/plugins temporarily and re-run diagnose to isolate the cause
3. Simplify the skaffold.yaml (drop experimental fields) to find the non-marshalable section
4. File a bug with the wrapped error if a plain config still fails

Example fix

// before: diagnose fails on exotic config
// after: validate the config parses and round-trips
skaffold diagnose --yaml-only   # or
skaffold config list            # sanity check CLI works on same config

err := diagnose(); err != nil {
    if strings.Contains(err.Error(), "marshalling configuration:") {
        // config contains unmarshalable data — test with a minimal skaffold.yaml
    }
}

When it happens

Trigger: `skaffold diagnose` calls yaml.MarshalWithSeparator(configs) and the marshaller returns an error, typically because configs contain an unsupported value type after custom deserialization or a versioned-config conversion.

Common situations: Using skaffold with custom transform/extension plugins that inject non-marshalable values; version skew between skaffold binary and config schema producing unrepresentable fields.

Related errors

• marshaling new config: %w
• missing apiVersion
• validating upgraded config: %w
• invalid skaffold config: %w
• parsing skaffold config: %w

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/38c42020683b5b42. Report an issue: GitHub.