Fatal error: Cannot instantiate interface in Magento 2?

Question

As the part of creating bundle product programmatically in Magento 2. I am getting below error. Even i removed var/cache and generation.

This may be a duplicate question but none of the answer is working for this issue.

Fatal error: Cannot instantiate interface Magento\Catalog\Api\Data\ProductExtensionInterface in \ObjectManager\Factory\Dynamic\Developer.php on line 73

Used below code as the reference of link

$productExtension = $objectManager->create(\Magento\Catalog\Api\Data\ProductExtensionInterface::class);
$option = $objectManager->create(\Magento\Bundle\Api\Data\OptionInterface::class);
$option->setTitle('Size');
$option->setType('radio');
$option->setRequired(true);
$option->setPosition(1);
//$option->setProductLinks($links);
$productExtension->setBundleOptions([$option]);
$_product->setExtensionAttributes($productExtension);

I am using object manager for temporary/quick purpose, will convert the object manager to constructor injunction.

Any one can help me on this issue.

Answer 1

I think you have not mentioned the preference in your di.xml. I also faced the same issue when I was creating custom config xml file module.

I got the issue when I called this code:

$testConfig = $this->_objectManager->get('Training\Test\Model\Config\ConfigInterface');
$myNodeInfo = $testConfig->getMyNodeInfo();

Below is the sample code I have added in my di.xml, may be it may help you to get reference:

<preference for="Training\Test\Model\Config\ConfigInterface" type="Training\Test\Model\Config" />

Here I have implemented the interface in Training\Test\Model\Config class and my getMyNodeInfo() method is defined in that Model.

So based on the the preference defined in di.xml the code ->get('Training\Test\Model\Config\ConfigInterface'); will create an object of type Training\Test\Model\Config.

Answer 2

I struggled with this and then found a solution that worked for me in the documentation.

Be sure to add your interface as a preference (correctly) in the di.xml, and then run php bin/magento setup:di:compile.

Answer 3

You should not use the ObjectManager.

Collect your dependencies via _constructor.

In case your interface still won't be loaded, check your di.xml and validate that a preference is available.

Answer 4

I tried this mentioned in another thread but it didn't solve:

redis-cli flushall

Finally, got solved by running setup:upgrade:

bin/magento setup:upgrade

# also run, if in production mode
bin/magento setup:static-content:deploy
bin/magento setup:di:compile

Answer 5

Please make sure module is enabled. You can verify using {{MagentoRoot}}/app/etc/config.php file. In my case module was disabled.

Answer 6

I have faced the similar issue i.e. cannot instantiate interface for some third party module.
The reason that I found out after debugging that the corresponding module's entry was missing from the app/etc/config.php but the module's code was present in the codebase.
After manually adding the module's entry in the app/etc/config.php file, the issue got resolved.

Answer 7

If anyone meets this bug, you should check if you declare an inherence from the interface to the implemented class in di.xml with preference tag. Then run bin/magento setup:upgrade to remove var/generation and cache. For production, you also need to run:

bin/magento setup:static-content:deploy
bin/magento setup:di:compile