hasura/graphql-engine · error

cue formatting error: %w

Error message

cue formatting error: %w

What it means

Thrown by metadatautil.YAMLToJSON when format.Node fails to pretty-print the CUE expression that was just successfully extracted from YAML. This is an internal CUE formatting failure, not a user YAML syntax problem — extraction already succeeded. It is rare and usually indicates a malformed/unexpected AST node produced by the extractor.

Source

Thrown at cli/internal/metadatautil/yaml.go:220

	_, err := resolveTags(map[string]string{baseDirectoryKey: baseDirectory}, node, &filenames)
	if err != nil {
		return filenames, errors.E(op, err)
	}

	return filenames, nil
}

func YAMLToJSON(yamlbs []byte) ([]byte, error) {
	var op errors.Op = "metadatautil.YAMLToJSON"

	cueExpr, err := cueyaml.Extract("", yamlbs)
	if err != nil {
		return nil, errors.E(op, fmt.Errorf("cue extraction error: %w", err))
	}

	cueNode, err := format.Node(cueExpr)
	if err != nil {
		return nil, errors.E(op, fmt.Errorf("cue formatting error: %w", err))
	}

	cueValue := cuecontext.New().CompileBytes(cueNode)

	jsonString, err := cuejson.Marshal(cueValue)
	if err != nil {
		return nil, errors.E(op, err)
	}

	return []byte(jsonString), nil
}

View on GitHub (pinned to 724551b9ae)

Solutions

1. Simplify the YAML: remove anchors, aliases, merge keys (<<:) and multi-document separators (---)
2. Convert the YAML to JSON with an external tool (yq -o=json) and use JSON metadata instead
3. Report upstream to the CUE project with the minimal YAML that reproduces it

Example fix

// before: metadata.yaml using a merge key
// defaults: &defaults
//   timeout: 10
// x:
//   <<: *defaults

// after: expand anchors explicitly
// defaults:
//   timeout: 10
// x:
//   timeout: 10

jsonOut, err := metadatautil.YAMLToJSON(data)
if err != nil && strings.Contains(err.Error(), "cue formatting error") {
	// fall back to a plain YAML->JSON converter
	jsonOut, err = yamlToJSONGeneric(data)
}

When it happens

Trigger: Calling YAMLToJSON on YAML that parses but contains exotic constructs (complex anchors, merge keys, unusual scalar forms) that produce a CUE AST format.Node cannot render. Practically any YAMLToJSON caller can surface it, but the extraction step (error 290) fails far more often.

Common situations: Rare; seen with unusual YAML generated by other tools (Ansible-style anchors, multi-document YAML pasted into metadata.yaml). Essentially never hit on server-exported metadata.

Related errors

• cue extraction error: %w
• cannot build %s from project: %w
• error getting actions file content: %w
• error in creating action: %w
• failed to get the matching platform for plugin %s: %w

AI-assisted analysis of hasura/graphql-engine@724551b9ae (2026-08-28). Data as JSON: /api/errors/6a625132f1101dab. Report an issue: GitHub.