weaviate/weaviate · warning

could not marshal resolve alias response: %w

Error message

could not marshal resolve alias response: %w

What it means

This wraps the json.Marshal error that occurs while serializing the QueryResolveAliasResponse (containing the resolved root class) back to the caller. It is an internal response-encoding failure, not a problem with the request.

Source

Thrown at cluster/schema/manager_alias.go:86

}

func (s *SchemaManager) ResolveAlias(req *command.QueryRequest) ([]byte, error) {
	subCommand := command.QueryResolveAliasRequest{}
	if err := json.Unmarshal(req.SubCommand, &subCommand); err != nil {
		return []byte{}, fmt.Errorf("%w: %w", ErrBadRequest, err)
	}

	rootClass := s.schema.ResolveAlias(subCommand.Alias)
	if rootClass == "" {
		return nil, fmt.Errorf("resolve alias: %s, %w", subCommand.Alias, ErrAliasNotFound)
	}

	response := command.QueryResolveAliasResponse{
		Class: rootClass,
	}
	payload, err := json.Marshal(&response)
	if err != nil {
		return []byte{}, fmt.Errorf("could not marshal resolve alias response: %w", err)
	}
	return payload, nil
}

func (s *SchemaManager) GetAliases(req *command.QueryRequest) ([]byte, error) {
	subCommand := command.QueryGetAliasesRequest{}
	if err := json.Unmarshal(req.SubCommand, &subCommand); err != nil {
		return []byte{}, fmt.Errorf("%w: %w", ErrBadRequest, err)
	}

	response := command.QueryGetAliasesResponse{
		Aliases: s.schema.getAliases(subCommand.Alias, subCommand.Class),
	}
	payload, err := json.Marshal(&response)
	if err != nil {
		return []byte{}, fmt.Errorf("could not marshal get aliases response: %w", err)
	}
	return payload, nil

View on GitHub (pinned to 75aa4b6d11)

Solutions

1. Inspect the wrapped inner error for the exact marshal failure reason.
2. Check whether the command.QueryResolveAliasResponse struct was recently modified with non-JSON-serializable fields and fix the type or add a Marshaler.
3. Retry the query — transient runtime issues rarely cause this, so persistence indicates a code/config problem.

payload, err := mgr.ResolveAlias(req)
if err != nil {
  var marshalErr error
  if strings.Contains(err.Error(), "could not marshal resolve alias response") {
    marshalErr = err // response-encoding bug: report and retry once
  }
  return fmt.Errorf("resolve alias failed: %w", err)
}

When it happens

Trigger: json.Marshal fails on the QueryResolveAliasResponse struct. In practice this is nearly impossible with a plain string field; it would require a corrupted marshaller state or a non-serializable value introduced by future field changes.

Common situations: Essentially only seen when the command package response struct is extended with custom types lacking JSON marshalling, or in exotic environments where encoding/json misbehaves.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• could not marshal get aliases response: %w
• marshal class %q metadata: %w
• marshal shard %q metadata: %w
• marshal request: %w
• failed to unmarshal query result: %w

AI-assisted analysis of weaviate/weaviate@75aa4b6d11 (2026-09-04). Data as JSON: /api/errors/e44ecdbd1d885f81. Report an issue: GitHub.