Null order in Magento\Sales\Block\Order\PrintShipment.php

[dnadle]

Viewing an order in the customer dashboard and clicking the print order link causes the following entry in httpd error_log:

PHP Fatal error: Call to a member function getRealOrderId() on null in /vendor/magento/module-sales/Block/Order/PrintShipment.php on line 58

Preconditions

Magento 2.1.6

Steps to reproduce

Log in as customer, go to Account Dashboard. Click My Orders, choose an order and click View Order, then click Print Order.

Expected result

No error in httpd error_log.

Actual result

The error described above is logged.

[YevSent]

Hi, @dnadle, please, provide additional details to reproduce this issue, like products in the order, shipment, etc. I've checked on Magento 2.1.6 and there are no any errors in Magento and Apache logs.

[dnadle]

I stepped through the code. The backend is trying to load the "current" order from a registry but the order is null, and this is not checked before the call to order->getRealOrderId() on line 58. The print version of the order is generated anyway and looks correct.

So, to reproduce the issue one must figure out why the order retrieved from the registry would be null. Regardless of any specific aspects of the order, calling a function on an object that could be null is bad code. It's a bug and should be fixed.

[bve-9384]

I experience the same issue, using Magento 2.1.7.
PHP Fatal error: Uncaught Error: Call to a member function getRealOrderId() on null in .../magento2/vendor/magento/module-sales/Block/Order/PrintShipment.php:58

Page URL: /sales/order/print/order_id/123/
Same issue for all orders, but page still looks fine

[veloraven]

Internal ticket was created: MAGETWO-69787

[dnadle]

This has something to do with full page caching. PrintShipment::_prepareLayout() is called 4 times successfully by an execution chain renders the print version of the order correctly. But then it is called again, by a different chain for which the registry is not properly initialized and this _prepareLayout() call exits with the fatal error. I don't yet know what is triggering this second rendering, but if you disable full page caching it does not occur and there is no error message logged.