Changing phtml file via /app

In a previous question i asked where to find items.phtml file. I found it and did the configuration and it worked. But when i did this it was via this path: vendor/magento/module-shipping/view/adminhtml/templates/create/items.phtml. I read somewhere that they do not recommend to any changes via /vendor but do this via /app/design/adminhtml/custom_vendor/custom_theme/ and so on. What i…

Magento 2: \Magento\Sales\Model\OrderRepository is not working in observer

$orderId = $order->getId(); $objectManager = $this->dataHelper->getObjectManager(); $order12 = $objectManager->create(‘\Magento\Sales\Model\OrderRepository’)->get($orderId); This code is not working in the observer. I am sending data through rest API. Getting issue in the console: Failed to load resource: the server responded with a status of 500 (Internal Server Error) Can you please provide the solution? Thanks