labstack/echo · error

ErrValidatorNotRegistered

ErrValidatorNotRegistered

Error message

validator not registered

What it means

ErrValidatorNotRegistered is returned by Context.Validate when c.echo.Validator is nil. Validate delegates to the registered Validator interface; with nothing registered there is no validation logic to run, so Echo refuses rather than silently passing validation.

Source

Thrown at httperror.go:30

// The following errors can produce HTTP status code by implementing HTTPStatusCoder interface
var (
	ErrBadRequest                  = &httpError{http.StatusBadRequest}            // 400
	ErrUnauthorized                = &httpError{http.StatusUnauthorized}          // 401
	ErrForbidden                   = &httpError{http.StatusForbidden}             // 403
	ErrNotFound                    = &httpError{http.StatusNotFound}              // 404
	ErrMethodNotAllowed            = &httpError{http.StatusMethodNotAllowed}      // 405
	ErrRequestTimeout              = &httpError{http.StatusRequestTimeout}        // 408
	ErrStatusRequestEntityTooLarge = &httpError{http.StatusRequestEntityTooLarge} // 413
	ErrUnsupportedMediaType        = &httpError{http.StatusUnsupportedMediaType}  // 415
	ErrTooManyRequests             = &httpError{http.StatusTooManyRequests}       // 429
	ErrInternalServerError         = &httpError{http.StatusInternalServerError}   // 500
	ErrBadGateway                  = &httpError{http.StatusBadGateway}            // 502
	ErrServiceUnavailable          = &httpError{http.StatusServiceUnavailable}    // 503
)

// The following errors fall into 500 (InternalServerError) category
var (
	ErrValidatorNotRegistered = errors.New("validator not registered")
	ErrRendererNotRegistered  = errors.New("renderer not registered")
	ErrInvalidRedirectCode    = errors.New("invalid redirect status code")
	ErrCookieNotFound         = errors.New("cookie not found")
	ErrInvalidCertOrKeyType   = errors.New("invalid cert or key type, must be string or []byte")
	ErrInvalidListenerNetwork = errors.New("invalid listener network")
)

// HTTPStatusCoder is an interface that errors can implement to produce status code for HTTP response
type HTTPStatusCoder interface {
	StatusCode() int
}

// StatusCode returns status code from err if it implements HTTPStatusCoder interface.
// If err does not implement the interface, it returns 0.
func StatusCode(err error) int {
	var sc HTTPStatusCoder
	if errors.As(err, &sc) {
		return sc.StatusCode()

View on GitHub (pinned to 05489dc173)

Solutions

1. Register a validator: e.Validator = &myValidator{} where myValidator implements echo.Validator (Validate(any) error)
2. Use the popular go-playground/validator wrapper (echo-contrib echovault or custom adapter)
3. Guard handler code: only call c.Validate if e.Validator != nil

Example fix

// before — handler calls Validate but no validator registered
e := echo.New()
e.GET("/u", func(c echo.Context) error {
    u := new(User)
    c.Bind(u)
    return c.Validate(u) // ErrValidatorNotRegistered
})

// after
e := echo.New()
e.Validator = &CustomValidator{validator: validate.New()}

// Guard Validate calls
if c.Echo().Validator != nil {
    if err := c.Validate(obj); err != nil {
        return err
    }
}

if err := c.Validate(obj); err != nil {
    if errors.Is(err, echo.ErrValidatorNotRegistered) {
        // validation skipped; proceed or log a warning
        return nil
    }
    return echo.NewHTTPError(http.StatusBadRequest, err.Error())
}

When it happens

Trigger: Calling c.Validate(obj) in a handler without first setting e.Validator = &CustomValidator{} on the Echo instance. Common when following a tutorial that adds c.Validate calls but skips the validator registration step.

Common situations: Forgetting to register the validator in main.go. Using a different Echo instance for testing than the one configured with the validator. Removing the validator registration during a refactor.

Related errors

• echo basic-auth middleware requires a validator function
• echo body-dump middleware requires a handler function
• invalid gzip level
• panic: err from config.ToMiddleware() in RequestLoggerWithCo
• ErrInvalidRedirectCode

AI-assisted analysis of labstack/echo@05489dc173 (2026-08-04). Data as JSON: /data/errors/32a8eaa4b25b8432.json. Report an issue: GitHub.