argoproj/argo-workflows · error

failed to unmarshal YAML %q: %w

Error message

failed to unmarshal YAML %q: %w

What it means

MustUnmarshal fell through to YAML parsing (input not '@' or '{') and yaml.UnmarshalStrict rejected the document — strict mode fails on unknown or duplicate fields. The panic message embeds the offending text.

Source

Thrown at pkg/apis/workflow/v1alpha1/marshall.go:37

	case []byte:
		if len(x) == 0 {
			panic("no text to unmarshal")
		}
		switch x[0] {
		case '@':
			filename := string(x[1:])
			y, err := os.ReadFile(filepath.Clean(filename))
			if err != nil {
				panic(fmt.Errorf("failed to read file %s: %w", filename, err))
			}
			MustUnmarshal(y, v)
		case '{':
			if err := json.Unmarshal(x, v); err != nil {
				panic(fmt.Errorf("failed to unmarshal JSON %q: %w", string(x), err))
			}
		default:
			if err := yaml.UnmarshalStrict(x, v); err != nil {
				panic(fmt.Errorf("failed to unmarshal YAML %q: %w", string(x), err))
			}
		}
	default:
		panic(fmt.Errorf("cannot unmarshal type %T", text))
	}
}

func MustMarshallJSON(v any) string {
	data, err := json.Marshal(v)
	if err != nil {
		panic(err)
	}
	return string(data)
}

func MustUnmarshalClusterWorkflowTemplate(text any) *ClusterWorkflowTemplate {
	x := &ClusterWorkflowTemplate{}
	MustUnmarshal(text, &x)

View on GitHub (pinned to 35bff19146)

Solutions

1. Remove unknown/mistyped fields from the YAML
2. Check for duplicate keys, which strict unmarshalling rejects

When it happens

Trigger: Thrown at pkg/apis/workflow/v1alpha1/marshall.go:37 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of argoproj/argo-workflows@35bff19146 (2026-09-03). Data as JSON: /api/errors/6e5485fdec0b9ba8. Report an issue: GitHub.