symfony/http-kernel · error · LogicException

You cannot use " " as the HttpClient component is not…

Error message

You cannot use "%s" as the HttpClient component is not installed. Try running "composer require symfony/http-client".

What it means

HttpClientKernel lets the test client route requests through symfony/http-client instead of a real HTTP kernel. Constructing it without providing an HttpClientInterface while the symfony/http-client component is not installed throws this LogicException at __construct time.

Solutions

1. Run composer require symfony/http-client
2. Or explicitly pass an HttpClientInterface instance to the constructor
3. Or remove/avoid HttpClientKernel and use KernelBrowser directly

Example fix

// before
$kernel = new HttpClientKernel($httpKernel);
// after
composer require symfony/http-client
$kernel = new HttpClientKernel($httpKernel); // or: new HttpClientKernel($httpKernel, $myClient)

if (!class_exists(\Symfony\Component\HttpClient\HttpClient::class)) {
    throw new \LogicException('symfony/http-client required for HttpClientKernel; run composer require symfony/http-client');
}
$kernel = new HttpClientKernel($httpKernel);

try {
    $client = new HttpClientKernel($httpKernel);
} catch (\LogicException $e) {
    // fall back to the plain kernel browser
    $client = new KernelBrowser($httpKernel);
}

When it happens

Trigger: new HttpClientKernel() (or DI auto-wiring it) with no client argument in a project where symfony/http-client is absent.

Common situations: Using the test framework's HTTP client abstraction without composer require symfony/http-client; moving code to a production build without dev requirements.

Understand the failure class

Background: "not installed", "pip install", "required for": how missing-dependency errors surface across open-source libraries — this error's family across 34 libraries.

Related errors

• You cannot pass non-empty bodies as the Mime component is…
• Cannot evaluate Expression for controllers since no…
• The "symfony/serializer" component is required to use the "#
• Request payload contains invalid "form" data.
• Unsupported format: " ".

AI-assisted analysis of symfony/http-kernel@aa3a39d728 (2026-09-13). Data as JSON: /api/errors/511766adc6090ed6. Report an issue: GitHub.

Appendix: source

Thrown at HttpClientKernel.php:39

use Symfony\Component\Mime\Part\TextPart;
use Symfony\Contracts\HttpClient\HttpClientInterface;

// Help opcache.preload discover always-needed symbols
class_exists(ResponseHeaderBag::class);

/**
 * An implementation of a Symfony HTTP kernel using a "real" HTTP client.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
final class HttpClientKernel implements HttpKernelInterface
{
    private HttpClientInterface $client;

    public function __construct(?HttpClientInterface $client = null)
    {
        if (null === $client && !class_exists(HttpClient::class)) {
            throw new \LogicException(\sprintf('You cannot use "%s" as the HttpClient component is not installed. Try running "composer require symfony/http-client".', __CLASS__));
        }

        $this->client = $client ?? HttpClient::create();
    }

    public function handle(Request $request, int $type = HttpKernelInterface::MAIN_REQUEST, bool $catch = true): Response
    {
        $headers = $this->getHeaders($request);
        $body = '';
        if (null !== $part = $this->getBody($request)) {
            $headers = array_merge($headers, $part->getPreparedHeaders()->toArray());
            $body = $part->bodyToIterable();
        }
        $response = $this->client->request($request->getMethod(), $request->getUri(), [
            'headers' => $headers,
            'body' => $body,
        ] + $request->attributes->get('http_client_options', []));

View on GitHub (pinned to aa3a39d728)