symfony/http-kernel · error · LogicException

Controller attributes cannot contain non-scalar/non-null…

Error message

Controller attributes cannot contain non-scalar/non-null values (value for key "%s" is not a scalar or null).

What it means

FragmentUriGenerator::checkNonScalar() throws LogicException when controller attributes contain arrays nested with non-scalar, non-null values. Fragment attributes are serialized into the URL query string, so only scalars and null survive the round trip.

Solutions

1. Pass only scalars (int, string, bool, float) or null as attributes; pass identifiers (e.g. entity id) instead of objects.
2. Remove the offending attribute or fetch the object inside the fragment controller.
3. Pass $strict = false to skip the check only if you understand the value will be mangled in the URL.

Example fix

// before
$ref = new ControllerReference('App\Controller\FragmentController::show', ['product' => $product]);
// after
$ref = new ControllerReference('App\Controller\FragmentController::show', ['productId' => $product->getId()]);

foreach ($attributes as $k => $v) { if (!is_scalar($v) && null !== $v) { throw new \InvalidArgumentException("Attribute '$k' must be scalar or null"); } }

function hasOnlyScalarAttributes(array $attrs): bool { foreach ($attrs as $v) { if (is_array($v)) { return hasOnlyScalarAttributes($v); } if (!is_scalar($v) && null !== $v) { return false; } } return true; }

When it happens

Trigger: Passing a ControllerReference whose attributes include objects, resources, or nested arrays holding such values, e.g. generate(new ControllerReference('App\Controller::show', ['entity' => $object])).

Common situations: Passing entities or value objects as fragment controller arguments; forgetting that URL generation flattens attributes to query parameters.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

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AI-assisted analysis of symfony/http-kernel@aa3a39d728 (2026-09-13). Data as JSON: /api/errors/374e67b9978e9f69. Report an issue: GitHub.

Appendix: source

Thrown at Fragment/FragmentUriGenerator.php:83

        // we need to sign the absolute URI, but want to return the path only.
        $fragmentUri = $sign || $absolute ? $request->getUriForPath($path) : $request->getBaseUrl().$path;

        if (!$sign) {
            return $fragmentUri;
        }

        $fragmentUri = $this->signer->sign($fragmentUri, $this->expiration);

        return $absolute ? $fragmentUri : substr($fragmentUri, \strlen($request->getSchemeAndHttpHost()));
    }

    private function checkNonScalar(array $values): void
    {
        foreach ($values as $key => $value) {
            if (\is_array($value)) {
                $this->checkNonScalar($value);
            } elseif (!\is_scalar($value) && null !== $value) {
                throw new \LogicException(\sprintf('Controller attributes cannot contain non-scalar/non-null values (value for key "%s" is not a scalar or null).', $key));
            }
        }
    }
}

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