kubernetes/kops · error

error converting to yaml: %v

Error message

error converting to yaml: %v

What it means

ToRawYaml marshals an arbitrary Go object to YAML bytes using utils.YamlMarshal and wraps any marshal failure in this error. Failures are rare because YAML marshalling of plain structs/slices seldom fails, but unsupported types (e.g. channels, funcs, cyclic pointers) or an internal encoder error will trigger it. The function is deprecated in favor of the kopscodecs API machinery.

Source

Thrown at pkg/apis/kops/parse.go:78

	configString := string(data)
	configString = strings.TrimSpace(configString)

	if configString != "" {
		err := yaml.Unmarshal([]byte(configString), dest, yaml.DisallowUnknownFields)
		if err != nil {
			return fmt.Errorf("error parsing configuration: %v", err)
		}
	}

	return nil
}

// ToRawYaml marshals an object to yaml, without the full api machinery
// Deprecated: prefer using the API machinery (package kopscodecs)
func ToRawYaml(obj interface{}) ([]byte, error) {
	data, err := utils.YamlMarshal(obj)
	if err != nil {
		return nil, fmt.Errorf("error converting to yaml: %v", err)
	}

	return data, nil
}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Inspect the wrapped %v error to find the non-serializable value; remove or replace that field.
2. Follow the deprecation notice: switch to the kopscodecs API machinery (serialization via the typed API) instead of ToRawYaml.
3. If marshalling a generated/dynamic object, sanitize it (e.g. convert to a plain map or typed struct) before marshalling.
4. Nil-check the object and ensure initialized, typed values rather than raw interfaces.

Example fix

// before
out, err := kops.ToRawYaml(objWithChannel) // unsupported field
// after
objWithChannel.Ch = nil // or use kopscodecs serialization
out, err := kopscodecs.ToYAML(objWithChannel)

data, err := kops.ToRawYaml(obj)
if err != nil {
	return fmt.Errorf("object %T not yaml-serializable: %w", obj, err)
}

When it happens

Trigger: Calling ToRawYaml with an object containing a value the YAML encoder cannot serialize — channels, function values, cyclic data structures, or invalid map keys — from callers like RunToolboxDump, writeAuthenticationConfig, or task validation in tests.

Common situations: Dumping a dynamically-built object that accidentally holds a non-serializable value; a struct field of unsupported type added by a recent code change; marshalling an empty/nil interface from an uninitialized config in test helpers like ValidateTasks.

Related errors

• unable to marshal YAML: %v
• marshaling to yaml for %v: %w
• error marshaling manifest to yaml: %v
• error serializing addons yaml: %v
• error serializing addons: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/915ce4240274a251. Report an issue: GitHub.