hyperledger/fabric · error

type name mismatch '%s' != '%s'

Error message

type name mismatch '%s' != '%s'

What it means

Serializer.Deserialize guard: the stored metadata's type name for a field-set does not match the Go struct name being deserialized into — the struct type changed between serialization and deserialization.

Source

Thrown at core/chaincode/lifecycle/serializer.go:332

		}
	}
	isSerialized = len(mismatches) == 0
	return
}

// Deserialize accepts a struct (of a type previously serialized) and populates it with the values from the db.
// Note: The struct names for the serialization and deserialization must match exactly.  Unencoded fields are not
// populated, and the extraneous keys are ignored.  The metadata provided should have been returned by a DeserializeMetadata
// call for the same namespace and name.
func (s *Serializer) Deserialize(namespace, name string, metadata *lb.StateMetadata, structure any, state ReadableState) error {
	value, _, err := s.SerializableChecks(structure)
	if err != nil {
		return errors.WithMessagef(err, "could not deserialize namespace %s/%s to unserializable type %T", namespace, name, structure)
	}

	typeName := value.Type().Name()
	if typeName != metadata.Datatype {
		return errors.Errorf("type name mismatch '%s' != '%s'", typeName, metadata.Datatype)
	}

	for i := 0; i < value.NumField(); i++ {
		fieldName := value.Type().Field(i).Name
		fieldValue := value.Field(i)
		switch fieldValue.Kind() {
		case reflect.String:
			oneOf, err := s.DeserializeFieldAsString(namespace, name, fieldName, state)
			if err != nil {
				return err
			}
			fieldValue.SetString(oneOf)
		case reflect.Int64:
			oneOf, err := s.DeserializeFieldAsInt64(namespace, name, fieldName, state)
			if err != nil {
				return err
			}
			fieldValue.SetInt(oneOf)

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Use the same struct type (name) that was used when the state was serialized
2. Migrate the stored data or rename the struct back to match

When it happens

Trigger: Thrown at core/chaincode/lifecycle/serializer.go:332 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/71aab7ec97b0ea05. Report an issue: GitHub.