# UnsupportedMediaTypeException

**Kind:** Class

**Source:** [`packages/common/exceptions/unsupported-media-type.exception.ts`](https://github.com/nestjs/nest/blob/master/packages/common/exceptions/unsupported-media-type.exception.ts#L11)

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

Defines an HTTP exception for *Unsupported Media Type* type errors.

`UnsupportedMediaTypeException` represents an HTTP 415 error, indicating that the server cannot process a request because its `Content-Type` is unsupported. It is typically thrown by controllers, guards, or middleware during request validation so NestJS can return a standardized HTTP error response.

**Extends:** `HttpException`

## Diagram

```mermaid
graph LR
  A[Client request] --> B[Content-Type validation]
  B -->|Supported media type| C[Controller handler]
  B -->|Unsupported media type| D[UnsupportedMediaTypeException]
  D --> E[HTTP 415 response]
```

## Usage

```ts
import {
  Controller,
  Post,
  Headers,
  UnsupportedMediaTypeException,
} from '@nestjs/common';

@Controller('uploads')
export class UploadController {
  @Post()
  upload(@Headers('content-type') contentType?: string) {
    if (!contentType?.startsWith('image/png')) {
      throw new UnsupportedMediaTypeException(
        'Only image/png uploads are supported.',
      );
    }

    return { message: 'Upload accepted' };
  }
}
```

## AI Coding Instructions

- Throw this exception when validation fails specifically because the request media type or `Content-Type` header is unsupported.
- Prefer HTTP 415 over `BadRequestException` when the request body format is valid but its declared media type is not accepted.
- Validate media types with `startsWith()` when parameters such as `charset` or multipart boundaries may be present.
- Provide a clear error message describing the accepted media types for API consumers.
- Use NestJS exception filters or the default exception handling pipeline rather than manually constructing HTTP 415 responses.