Why Is prepareResponse method being called twice in Laravel Router?

[treevel]

Laravel Version

11.48.0

Description

I noticed that prepareResponse() is called twice during a single request in Laravel Router.

From what I understand:

• It is called inside runRouteWithinStack after route->run().
• It is called again in runRoute with the result returned from runRouteWithinStack.
• I want to confirm whether this is expected behavior by design, and why Laravel needs both calls.

Also, this mean PreparingResponse and ResponsePrepared events will be dispatched twice for one request. Is that also expected behavior by design?

Related Code:

/**
 * Return the response for the given route.
 */
protected function runRoute(Request $request, Route $route)
{
    $request->setRouteResolver(fn () => $route);

    $this->events->dispatch(new RouteMatched($route, $request));

    return $this->prepareResponse($request,
        $this->runRouteWithinStack($route, $request)
    );
}

/**
 * Run the given route within a Stack "onion" instance.
 */
protected function runRouteWithinStack(Route $route, Request $request)
{
    $shouldSkipMiddleware = $this->container->bound('middleware.disable') &&
                            $this->container->make('middleware.disable') === true;

    $middleware = $shouldSkipMiddleware ? [] : $this->gatherRouteMiddleware($route);

    return (new Pipeline($this->container))
        ->send($request)
        ->through($middleware)
        ->then(fn ($request) => $this->prepareResponse(
            $request, $route->run()
        ));
}

[benjdiasaad]

This is actually expected behavior and part of how the router normalizes responses through the pipeline.

The first call to prepareResponse() happens inside runRouteWithinStack() after the route action is executed. At that point, the result can still be a variety of types (array, string, Responsable, etc.), so Laravel converts it into a proper Response instance.

Then, runRoute() calls prepareResponse() again on the result returned from the pipeline.

This second call acts as a final normalization step to ensure that anything coming out of the middleware stack is still a valid Response. This is important because middleware can modify or even replace the response.

So even if it looks redundant, it’s intentional:

• first call → normalize the controller result
• second call → ensure consistency after middleware execution

Regarding events like PreparingResponse and ResponsePrepared, yes they may be dispatched twice as a consequence of this design.

In practice, this doesn’t usually cause issues, but it’s something to keep in mind if you're listening to those events.

So overall, this behavior is by design rather than a bug.

[tareq-halaby]

Yes, this is intentional by design. The double call exists for a specific and important reason — let me explain each call's role.

Why prepareResponse() is called twice

Call 1 — Inside runRouteWithinStack()

This happens at the end of the middleware pipeline via the $next closure:

return (new Pipeline($this->container))
    ->send($request)
    ->through($middleware)
    ->then(fn ($request) => $this->prepareResponse(
        $request, $route->run()
    ));

At this point, $route->run() returns the raw output from your controller — which could be a string, an array, a Responsable object, a JsonResource, a View, etc. The first prepareResponse() call converts that raw return value into a proper Symfony\Component\HttpFoundation\Response instance before it travels back up through the middleware stack.

This is necessary because middleware needs to work with a Response object. If your controller returns ['key' => 'value'], middleware can't call ->header() or ->cookie() on a raw array.

Call 2 — Inside runRoute() on the pipeline result

return $this->prepareResponse(
    $request,
    $this->runRouteWithinStack($route, $request)
);

This second call wraps whatever the entire middleware stack returned. Middleware can replace or modify the response — for example, a caching middleware might return a completely different Response object, or a middleware could return a raw value itself. The second call ensures that no matter what the middleware stack produced, the final result is guaranteed to be a valid, properly prepared Response before it leaves the router.

Why both calls are needed

	Call 1	Call 2
Input	Raw controller return value	Result from entire middleware stack
Purpose	Normalize for middleware consumption	Guarantee final response validity
Can be skipped?	No — middleware needs a Response	No — middleware may have modified it

Regarding PreparingResponse / ResponsePrepared events

Yes — these events fire twice as a direct consequence. If you're listening to these events, be aware they will trigger once for the inner normalization and once for the final normalization. In practice this rarely causes issues unless you have side effects in those listeners (e.g., logging or modifying headers), in which case you'd need to guard against the double execution.

This is by design, not a bug, and has been this way since early versions of Laravel's routing layer.