π Error Handling
Catching Errorsβ
Return errors from route handlers and middleware so Fiber can handle them centrally.
- Example
app.Get("/", func(c fiber.Ctx) error {
// Pass error to Fiber
return c.SendFile("file-does-not-exist")
})
Fiber does not recover from panics by default. Add the Recover
middleware to catch panics in any handler:
package main
import (
"log"
"github.com/gofiber/fiber/v3"
"github.com/gofiber/fiber/v3/middleware/recover"
)
func main() {
app := fiber.New()
app.Use(recover.New())
app.Get("/", func(c fiber.Ctx) error {
panic("This panic is caught by fiber")
})
log.Fatal(app.Listen(":3000"))
}
Use fiber.NewError()
to create an error with a status code. If you omit the message, Fiber uses the standard status text (for example, 404
becomes Not Found
).
app.Get("/", func(c fiber.Ctx) error {
// 503 Service Unavailable
return fiber.ErrServiceUnavailable
// 503 On vacation!
return fiber.NewError(fiber.StatusServiceUnavailable, "On vacation!")
})
Default Error Handlerβ
Fiber ships with a default error handler that sends 500 Internal Server Error for generic errors. If the error is a fiber.Error, the response uses the embedded status code and message.
// Default error handler
var DefaultErrorHandler = func(c fiber.Ctx, err error) error {
// Status code defaults to 500
code := fiber.StatusInternalServerError
// Retrieve the custom status code if it's a *fiber.Error
var e *fiber.Error
if errors.As(err, &e) {
code = e.Code
}
// Set Content-Type: text/plain; charset=utf-8
c.Set(fiber.HeaderContentType, fiber.MIMETextPlainCharsetUTF8)
// Return status code with error message
return c.Status(code).SendString(err.Error())
}
Custom Error Handlerβ
Set a custom error handler in fiber.Config
when creating a new app.
The default handler covers most cases, but a custom handler lets you react to specific error typesβfor example, by logging to a service or sending a tailored JSON or HTML response.
The following example shows how to display error pages for different types of errors.
// Create a new fiber instance with custom config
app := fiber.New(fiber.Config{
// Override default error handler
ErrorHandler: func(ctx fiber.Ctx, err error) error {
// Status code defaults to 500
code := fiber.StatusInternalServerError
// Retrieve the custom status code if it's a *fiber.Error
var e *fiber.Error
if errors.As(err, &e) {
code = e.Code
}
// Send custom error page
err = ctx.Status(code).SendFile(fmt.Sprintf("./%d.html", code))
if err != nil {
// In case the SendFile fails
return ctx.Status(fiber.StatusInternalServerError).SendString("Internal Server Error")
}
// Return from handler
return nil
},
})
// ...
Special thanks to the Echo and Express frameworks for inspiring parts of this error-handling approach.