Os status codes na faixa dos 400 significam que houve um erro por parte do cliente.

Você se lembra de todos aqueles erros (e piadas) a respeito do "**404 Not Found**"?

## Use o `HTTPException`

Para retornar ao cliente *responses* HTTP com erros, use o `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"
{!../../../docs_src/handling_errors/tutorial001.py!}
```

var errDoneForNow = errors.New("done for now")

// errSkipFile returned by the fn() for readDirFn() when it needs
// to proceed to next entry.
var errSkipFile = errors.New("skip this file")

var errIgnoreFileContrib = errors.New("ignore this file's contribution toward data-usage")

// errXLBackend XL drive mode requires fresh deployment.
var errXLBackend = errors.New("XL backend requires fresh drive")

}

// toAPIErrorCode - Converts embedded errors. Convenience
// function written to handle all cases where we have known types of
// errors returned by underlying layers.
func toAPIErrorCode(ctx context.Context, err error) (apiErr APIErrorCode) {
	if err == nil {
		return ErrNone
	}

	// Errors that are generated by net.Conn and any context errors must be handled here.

// error returned when temporary account is not found
var errNoSuchTempAccount = errors.New("Specified temporary account does not exist")

// error returned in IAM subsystem when an account doesn't exist.
var errNoSuchAccount = errors.New("Specified account does not exist")

// error returned in IAM subsystem when groups doesn't exist.

package s3select

// /////////////////////////////////////////////////////////////////////
//
//	Validation errors.
//
// /////////////////////////////////////////////////////////////////////
func errExpressionTooLong(err error) *s3Error {
	return &s3Error{
		code:       "ExpressionTooLong",
		message:    "The SQL expression is too long: The maximum byte-length for the SQL expression is 256 KB.",

The status codes in the 400 range mean that there was an error from the client.

Remember all those **"404 Not Found"** errors (and jokes)?

## Use `HTTPException`

To return HTTP responses with errors to the client you use `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"
{!../../../docs_src/handling_errors/tutorial001.py!}
```

### Raise an `HTTPException` in your code

)

// writeSTSErrorResponse writes error headers
func writeSTSErrorResponse(ctx context.Context, w http.ResponseWriter, errCode STSErrorCode, err error) {
	stsErr := stsErrCodes.ToSTSErr(errCode)

	// Generate error response.
	stsErrorResponse := STSErrorResponse{}
	stsErrorResponse.Error.Code = stsErr.Code
	stsErrorResponse.RequestID = w.Header().Get(xhttp.AmzRequestID)
	stsErrorResponse.Error.Message = stsErr.Description
	if err != nil {

	return "Object name invalid: " + e.Bucket + "/" + e.Object
}

// Error returns string an error formatted as the given text.
func (e ObjectNameTooLong) Error() string {
	return "Object name too long: " + e.Bucket + "/" + e.Object
}

// Error returns string an error formatted as the given text.
func (e ObjectNamePrefixAsSlash) Error() string {

func isSysErrCrossDevice(err error) bool {
	return errors.Is(err, syscall.EXDEV)
}

// Check if given error corresponds to too many open files
func isSysErrTooManyFiles(err error) bool {
	return errors.Is(err, syscall.ENFILE) || errors.Is(err, syscall.EMFILE)
}

func osIsNotExist(err error) bool {
	return errors.Is(err, os.ErrNotExist)
}

func osIsPermission(err error) bool {

// Check if an API error is properly defined
func TestAPIErrCodeDefinition(t *testing.T) {
	for errAPI := ErrNone + 1; errAPI < apiErrCodeEnd; errAPI++ {
		errCode, ok := errorCodes[errAPI]
		if !ok {
			t.Fatal(errAPI, "error code is not defined in the API error code table")
		}
		if errCode.Code == "" {
			t.Fatal(errAPI, "error code has an empty XML code")
		}
		if errCode.HTTPStatusCode == 0 {