# NotFoundException

**Kind:** Class

**Source:** [`packages/common/exceptions/not-found.exception.ts`](https://github.com/nestjs/nest/blob/master/packages/common/exceptions/not-found.exception.ts#L11)

**Part of:** [Common](subsystem-packages-common)

Defines an HTTP exception for *Not Found* type errors.

`NotFoundException` represents an HTTP 404 error when a requested resource cannot be found. It extends the application's HTTP exception system, providing a consistent way for controllers and services to signal missing entities to the framework's exception handling layer.

**Extends:** `HttpException`

## Diagram

```mermaid
graph LR
  A[Controller or Service] -->|throws| B[NotFoundException]
  B --> C[HTTP Exception Handler]
  C --> D[HTTP 404 Not Found Response]
  D --> E[Client]
```

## Usage

```ts
import { NotFoundException } from '@nestjs/common';

async function findUserById(id: string) {
  const user = await usersRepository.findById(id);

  if (!user) {
    throw new NotFoundException(`User with ID "${id}" was not found`);
  }

  return user;
}
```

## AI Coding Instructions

- Throw `NotFoundException` when a requested resource does not exist or cannot be resolved by its identifier.
- Include a clear, safe error message that identifies the missing resource without exposing sensitive implementation details.
- Use this exception instead of manually constructing `{ statusCode: 404 }` response objects; the framework exception filter formats the HTTP response.
- Do not use `NotFoundException` for validation failures, authorization issues, or unexpected persistence errors; use the appropriate exception type instead.

## Used by

4 references from 4 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

### Imported by (4)

- `RoutesResolver` — `packages/core/router/routes-resolver.ts`:35
- `RecipesResolver` — `integration/graphql-code-first/src/recipes/recipes.resolver.ts`:13
- `RecipesResolver` — `sample/23-graphql-code-first/src/recipes/recipes.resolver.ts`:11
- `RecipesResolver` — `sample/33-graphql-mercurius/src/recipes/recipes.resolver.ts`:16