twigphp/Twig · error · RuntimeError

Impossible to invoke a method on a variable (dynamic…

Error message

Impossible to invoke a method on a variable (dynamic message).

What it means

Twig's CoreExtension::getAttribute() throws this RuntimeError when template code tries to call a method-like attribute ({{ var.item() }}) on a value that cannot have methods: an array is treated as a sequence/mapping, and other non-object values report their debug type. Twig aborts evaluation because method invocation is meaningless on that variable type.

Solutions

1. Fix the template to use the filter/function form for arrays (e.g. {{ items|length }}, {{ items|keys }}) instead of method calls
2. Convert the value passed to the template into an object (ArrayAccess or a class with the method)
3. Check the variable being passed from the controller/extension context; pass the intended object instead of an array
4. If the call is expected to be optional, guard with the 'defined' test before invoking

Example fix

// before (template)
{{ products.count() }}

// after
{{ products|length }}

// in a Twig extension or before render
if (!is_object($value) && !is_array($value)) { throw new \InvalidArgumentException('Expected object for method call in template'); }

function isMethodCallable($value, string $method): bool { return is_object($value) && method_exists($value, $method); }

try { $twig->render($tpl, $ctx); } catch (\Twig\Error\RuntimeError $e) { /* inspect $e->getMessage() for 'Impossible to invoke a method' */ }

When it happens

Trigger: Calling a dynamic method on an array (e.g. {{ items.count() }} where items is a PHP array), or on a scalar/null in a template, while type is Template::METHOD_CALL and the value is not an object with that method.

Common situations: Upgrading from versions/configs where arrays silently returned null; passing arrays where objects (e.g. ArrayAccess, Collection) were expected; typos like {{ foo.keys() }} on arrays; strict_variables differences across environments.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Failed to load Twig template
• The "cycle" function expects a non-empty sequence.
• The "random" function cannot pick from an empty sequence or…
• Regexp " " passed to "matches" failed: .
• Trimming side must be "left", "right" or "both".

AI-assisted analysis of twigphp/Twig@a414c3a491 (2026-09-13). Data as JSON: /api/errors/52f32ee8083062b5. Report an issue: GitHub.

Appendix: source

Thrown at src/Extension/CoreExtension.php:1846

        if (!\is_object($object)) {
            if ($isDefinedTest) {
                return false;
            }

            if ($ignoreStrictCheck || !$env->isStrictVariables()) {
                return;
            }

            if (null === $object) {
                $message = \sprintf('Impossible to invoke a method ("%s") on a null variable.', $item);
            } elseif (\is_array($object)) {
                $message = \sprintf('Impossible to invoke a method ("%s") on a sequence/mapping.', $item);
            } else {
                $message = \sprintf('Impossible to invoke a method ("%s") on a %s variable ("%s").', $item, get_debug_type($object), $object);
            }

            throw new RuntimeError($message, $lineno, $source);
        }

        if ($object instanceof Template) {
            throw new RuntimeError('Accessing \Twig\Template attributes is forbidden.', $lineno, $source);
        }

        // object property
        if (Template::METHOD_CALL !== $type) {
            if ($sandboxed) {
                try {
                    $env->getExtension(SandboxExtension::class)->getChecker()->checkPropertyAllowed($object, $item, $lineno, $source);
                } catch (SecurityNotAllowedPropertyError $propertyNotAllowedError) {
                    goto methodCheck;
                }
            }

            static $propertyCheckers = [];

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