TestCorsHandler handler1 = new TestCorsHandler("handler1");
        TestCorsHandler handler2 = new TestCorsHandler("handler2");
        TestCorsHandler handler3 = new TestCorsHandler("handler3");

        // Execute
        corsHandlerFactory.add(origin1, handler1);
        corsHandlerFactory.add(origin2, handler2);
        corsHandlerFactory.add(origin3, handler3);

        // Verify

Bir request geçersiz veri içerdiğinde, **FastAPI** içeride `RequestValidationError` raise eder.

Ve bunun için varsayılan bir exception handler da içerir.

Override etmek için `RequestValidationError`’ı import edin ve exception handler’ı `@app.exception_handler(RequestValidationError)` ile decorate edin.

Exception handler, bir `Request` ve exception’ı alır.

{* ../../docs_src/handling_errors/tutorial004_py310.py hl[2,14:19] *}

///

## Override the default exception handlers { #override-the-default-exception-handlers }

**FastAPI** has some default exception handlers.

These handlers are in charge of returning the default JSON responses when you `raise` an `HTTPException` and when the request has invalid data.

You can override these exception handlers with your own.

kullanan bir dependency kullanır, sonra o dependency içinde `except` ile bir exception yakalar ve exception'ı tekrar raise etmezseniz; exception otomatik olarak herhangi bir exception handler'a veya internal server error handler'a raise/forward edilirdi.

Bu davranış 0.110.0 sürümünde değiştirildi. Amaç, handler olmayan (internal server errors) forward edilmiş exception'ların yönetilmemesinden kaynaklanan bellek tüketimini düzeltmek ve bunu normal Python kodunun davranışıyla tutarlı hale getirmekti....

{* ../../docs_src/events/tutorial001_py310.py hl[8] *}

In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.

You can add more than one event handler function.

And your application won't start receiving requests until all the `startup` event handlers have completed.

### `shutdown` event { #shutdown-event }

///

## Die Default-Exceptionhandler überschreiben { #override-the-default-exception-handlers }

**FastAPI** hat einige Default-Exceptionhandler.

Diese Handler sind dafür verantwortlich, die Default-JSON-Responses zurückzugeben, wenn Sie eine `HTTPException` `raise`n und wenn der Request ungültige Daten enthält.

        }
    }

    /**
     * Loads protocol handlers from the specified base package by scanning for
     * Handler classes in subpackages and registering them as web or file protocols
     * based on their PROTOCOL_TYPE field.
     *
     * @param basePackage the base package to scan for protocol handlers
     */
    protected void loadProtocols(final String basePackage) {

participant client as Client
participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception
        dep -->> handler: Raise Exception

    /**
     * Dispatches an event to all registered handlers for the event name.
     *
     * @param event the event to dispatch.
     */
    protected void dispatchEvent(final EventInfo event) {
        final List<Consumer<EventInfo>> handlers = eventHandlers.get(event.name);
        if (handlers != null) {
            for (final Consumer<EventInfo> handler : handlers) {
                try {

{* ../../docs_src/handling_errors/tutorial002_py310.py hl[14] *}

## Установка пользовательских обработчиков исключений { #install-custom-exception-handlers }

Вы можете добавить пользовательские обработчики исключений с помощью [тех же утилит обработки исключений из Starlette](https://www.starlette.dev/exceptions/).