ratchetphp/Ratchet · error · InvalidArgumentException

Handler must be instance of SessionHandlerInterface

Error message

Handler must be instance of SessionHandlerInterface

What it means

VirtualSessionStorageForSymfony6::setSaveHandler throws InvalidArgumentException when the supplied save handler does not implement \SessionHandlerInterface. Like the base VirtualSessionStorage, it needs the interface so it can wrap the handler in VirtualProxy. The Symfony6 variant exists to satisfy Symfony 6 session storage signatures while keeping Ratchet's virtual session behavior.

Solutions

1. Pass an instance of \SessionHandlerInterface (e.g. \SessionHandler or a Symfony handler that implements the interface, such as NativeSessionHandler subclasses) to the constructor.
2. Verify the DI container wires a real \SessionHandlerInterface implementation, not the storage wrapper itself.
3. Add the interface to a custom handler class and implement all required methods with correct signatures.

Example fix

// before
new \Ratchet\Session\Storage\VirtualSessionStorageForSymfony6('sid'); // constructor given no handler
// after
new \Ratchet\Session\Storage\VirtualSessionStorageForSymfony6('sid', new \SessionHandler());

if (!$handler instanceof \SessionHandlerInterface) {
    throw new \InvalidArgumentException('VirtualSessionStorageForSymfony6 requires \SessionHandlerInterface');
}
$storage = new \Ratchet\Session\Storage\VirtualSessionStorageForSymfony6('sid', $handler);

function isSymfony6CompatibleHandler($h): bool { return $h instanceof \SessionHandlerInterface; }

try {
    $storage = new \Ratchet\Session\Storage\VirtualSessionStorageForSymfony6('sid', $handler);
} catch (\InvalidArgumentException $e) {
    $storage = new \Ratchet\Session\Storage\VirtualSessionStorageForSymfony6('sid', new \SessionHandler());
}

When it happens

Trigger: Constructing VirtualSessionStorageForSymfony6 (its constructor calls setSaveHandler) with null or a handler object lacking \SessionHandlerInterface; calling setSaveHandler directly with such a value.

Common situations: Integrating Ratchet sessions into a Symfony 6 app and passing Symfony's own session storage/handler classes that do not implement the plain \SessionHandlerInterface contract expected here; misconfiguring the session handler service.

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

• Argument #4 ($serializer) expected…
• Can not change session name in VirtualProxy
• Can not change session name in VirtualProxy
• Handler must be instance of SessionHandlerInterface
• Handler must be instance of SessionHandlerInterface

AI-assisted analysis of ratchetphp/Ratchet@e621c6c40b (2026-09-16). Data as JSON: /api/errors/5237579d7a7fbc8f. Report an issue: GitHub.

Appendix: source

Thrown at src/Ratchet/Session/Storage/VirtualSessionStorageForSymfony6.php:86

    public function save() {
        // get the data from the bags?
        // serialize the data
        // save the data using the saveHandler
//        $this->saveHandler->write($this->saveHandler->getId(),

        if (!$this->saveHandler->isWrapper() && !$this->getSaveHandler()->isSessionHandlerInterface()) {
            $this->saveHandler->setActive(false);
        }

        $this->closed = true;
    }

    /**
     * {@inheritdoc}
     */
    public function setSaveHandler($saveHandler = null) {
        if (!($saveHandler instanceof \SessionHandlerInterface)) {
            throw new \InvalidArgumentException('Handler must be instance of SessionHandlerInterface');
        }

        if (!($saveHandler instanceof VirtualProxy)) {
            $saveHandler = new VirtualProxy($saveHandler);
        }

        $this->saveHandler = $saveHandler;
    }
}

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