# invalid_deprecated_subclass_annotation

> Details about the invalid_deprecated_subclass_annotation diagnostic produced by the Dart analyzer.



_The annotation '@Deprecated.subclass' can only be applied to subclassable classes and mixins._

## Description

The analyzer produces this diagnostic when anything other than a
subclassable class or mixin is annotated with
`@Deprecated.subclass`. A subclassable
class is a class not declared with the `final` or `sealed` keywords. A
subclassable mixin is a mixin not declared with the `base` keyword.

## Example

The following code produces this diagnostic because the annotation is on a
sealed class:

```dart
@[!Deprecated.subclass!]()
sealed class C {}
```

## Common fixes

Remove the annotation:

```dart
sealed class C {}
```

