This issue is automatically created based on existing pull request: #40787: fix: adjustCreditMemoItemQuantities causes a fatal error on missing order/invoice

Preconditions and environment

• Magento version: 2.4.8-p4
• Admin user attempting to create a credit memo for an order
• Occurs when an invalid/missing order_id, creditmemo_id, or invoice_id is passed to the credit memo save action

Steps to reproduce

1. Navigate to Admin > Sales > Orders and open any order.
2. Attempt to create a credit memo by navigating directly to the credit memo save URL with an invalid or missing order_id / creditmemo_id parameter (e.g. via a stale or manipulated POST request to admin/sales/order_creditmemo/save).
3. Submit the form.

Expected result

The controller handles the failed credit memo load gracefully and redirects to the noroute page (or back with an appropriate error), without throwing a fatal error.

Actual result

A TypeError is thrown and logged as a CRITICAL error, crashing the request:

[2026-04-25T08:09:22.547554+00:00] main.CRITICAL: TypeError:
Magento\Sales\Controller\Adminhtml\Order\Creditmemo\Save::adjustCreditMemoItemQuantities():
Argument #1 ($creditMemo) must be of type Magento\Sales\Model\Order\Creditmemo, false given,
called in vendor/magento/module-sales/Controller/Adminhtml/Order/Creditmemo/Save.php on line 88
and defined in vendor/magento/module-sales/Controller/Adminhtml/Order/Creditmemo/Save.php:152

Additional information

Root cause: In Save::execute(), adjustCreditMemoItemQuantities($creditmemo) is called on line 94 before the if ($creditmemo) guard on line 95. When CreditmemoLoader::load() returns false, the typed method receives false instead of a Creditmemo instance, triggering the TypeError.

Fix: Move the adjustCreditMemoItemQuantities($creditmemo) call inside the if ($creditmemo) block so it is only invoked when a valid credit memo object has been loaded.

Release note

Fixed a TypeError crash in the admin credit memo save controller (Magento\Sales\Controller\Adminhtml\Order\Creditmemo\Save) that occurred when the credit memo could not be loaded. The adjustCreditMemoItemQuantities call is now correctly guarded by the existing if ($creditmemo) check.