yiisoft/yii2 · warning · InvalidConfigException

Failed to instantiate class "Instance". Required parameter "

Error message

Failed to instantiate class "Instance". Required parameter "id" is missing

What it means

yii\di\Instance implements magic __set_state() so that objects exported with var_export() can be reconstructed when the generated code is eval'd/included. If the exported state array lacks the 'id' key, reconstruction is impossible and __set_state() throws InvalidConfigException 'Failed to instantiate class "Instance". Required parameter "id" is missing'. In normal use var_export() always includes public properties, so this fires only when the state array was hand-built or altered.

Source

Thrown at framework/di/Instance.php:211

                return null;
            }
            throw $e;
        }
    }

    /**
     * Restores class state after using `var_export()`.
     *
     * @param array $state
     * @return Instance
     * @throws InvalidConfigException when $state property does not contain `id` parameter
     * @see https://www.php.net/manual/en/function.var-export.php
     * @since 2.0.12
     */
    public static function __set_state($state)
    {
        if (!isset($state['id'])) {
            throw new InvalidConfigException('Failed to instantiate class "Instance". Required parameter "id" is missing');
        }

        return new self($state['id']);
    }
}

View on GitHub (pinned to 66f00d18a2)

Solutions

Ensure the state array passed to Instance::__set_state() contains 'id', e.g. ['id' => 'cache'].
Don't strip public properties when post-processing var_export() output of Instance objects.
Prefer PHP serialize()/igbinary or a dedicated cache serializer over var_export for objects.

Example fix

// before
$instance = Instance::__set_state([]);

// after
$instance = Instance::__set_state(['id' => 'cache']);

Defensive patterns

Strategy: validation

Validate before calling

if (!isset($state['id'])) {
    throw new \InvalidArgumentException('Cannot restore Instance: state must contain an "id" key.');
}
$instance = \yii\di\Instance::__set_state($state);

Prevention

Never strip public properties from var_export() output that will be eval'd back into objects.
Prefer serialize()/unserialize() or Igbinary for object caching instead of var_export pipelines.
If you post-process exported state, assert array_key_exists('id', $state) before including the file.

When it happens

Trigger: Calling Instance::__set_state([]) (or an array without 'id') directly, e.g. in tests or custom serialization code; caching pipelines that var_export() an Instance, strip properties for size, and eval the result later.

Common situations: Opcache/config-cache systems based on var_export(); unit tests exercising __set_state; custom var_export-based dumps that filter keys and accidentally drop 'id'.

Related errors

AI-assisted analysis of yiisoft/yii2@66f00d18a2 (2026-08-17). Data as JSON: /api/errors/e72353c67235a18c. Report an issue: GitHub.