# undefined_annotation

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



_Undefined name '{0}' used as an annotation._

## Description

The analyzer produces this diagnostic when a name that isn't defined is
used as an annotation.

## Example

The following code produces this diagnostic because the name `undefined`
isn't defined:

```dart
[!@undefined!]
void f() {}
```

## Common fixes

If the name is correct, but it isn't declared yet, then declare the name as
a constant value:

```dart
const undefined = 'undefined';

@undefined
void f() {}
```

If the name is wrong, replace the name with the name of a valid constant:

```dart
@deprecated
void f() {}
```

Otherwise, remove the annotation.

