What causes "unknown value kind: %d, for value: %s" in dgraph-io/dgraph?

Inspect the reported value kind and route numeric/variable values to the appropriate converter

unknown value kind: %d, for value: %s

Error message

unknown value kind: %d, for value: %s

What it means

This is the fallback case of the GraphQL AST value-to-Go converter: the value node's Kind was not any recognized kind (Boolean, String, Block, Enum, Null). It indicates an unexpected/unhandled AST value kind reached the conversion function.

Source

Thrown at graphql/schema/wrappers.go:2992

		vars[value.Raw] = true
		return value.String(), nil
	case ast.IntValue:
		return strconv.ParseInt(value.Raw, 10, 64)
	case ast.FloatValue:
		return strconv.ParseFloat(value.Raw, 64)
	case ast.BooleanValue:
		return strconv.ParseBool(value.Raw)
	case ast.StringValue:
		return value.Raw, nil
	case ast.BlockValue, ast.EnumValue:
		if strictJSON {
			return nil, fmt.Errorf("found unexpected value: %s", value.String())
		}
		return value.Raw, nil
	case ast.NullValue:
		return nil, nil
	default:
		return nil, fmt.Errorf("unknown value kind: %d, for value: %s", value.Kind, value.String())
	}
}

// Given a template for a body with variables defined, this function parses the body
// and converts it into a JSON representation and returns that. It also returns a list of the
// variable names that are required by this template.
// for e.g.
// { author: $id, post: { id: $postID }}
// would return
// { "author" : "$id", "post": { "id": "$postID" }} and { "id": true, "postID": true}
// If the final result is not a valid JSON, then an error is returned.
//
// In strictJSON mode block strings and enums are invalid and throw an error.
// strictJSON should be false when the body template is being used for custom graphql arg parsing,
// otherwise it should be true.
func parseBodyTemplate(body string, strictJSON bool) (interface{}, map[string]bool, error) {
	if strings.TrimSpace(body) == "" {
		return nil, nil, nil

View on GitHub (pinned to 759e242be6)

Solutions

Inspect the reported value kind and route numeric/variable values to the appropriate converter
Upgrade/patch the library so the converter handles all value kinds
Pre-process the AST to inline variables before conversion

Defensive patterns

Strategy: try-catch

Try / catch

v, err := convertValue(node)
if err != nil {
  if strings.Contains(err.Error(), "unknown value kind") {
    log.Printf("unhandled AST kind %v", node.Kind)
    return handleUnknownKind(node) // custom branch
  }
  return err
}

Prevention

Keep the converter updated for all ast.Kind values
Inline/simplify variable and numeric nodes before conversion
Report unhandled kinds upstream as library bugs

When it happens

Trigger: A value node with an unhandled ast.Kind (e.g. IntValue/FloatValue or Variable if not handled elsewhere) is passed to this conversion function, hitting the default branch.

Common situations: Library bugs or custom AST construction, passing numeric or variable nodes into a converter that only expects string-like/null values, or version mismatch where new AST kinds aren't handled.

Related errors

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/ba359fd0d44f1697. Report an issue: GitHub.