I've just migrated my Magento 1.9 data to Magento 2.3.1.
Everything works well, but in certain circonstances, I can't ship the order in the back end.
Let's take an example.
I place an order for a product that has stock = 0 but where backorder is configured as "Allow quantity below 0".
So the order is placed without any problem.
Now when trying to ship this order, I have the following message:
Source item not found by source code: default and sku: Jupon-Vivianna-H2-220cm-Ivoire-50 (4XL).
First guess was salable quantity is blank, so I went on Stores > Configuration > Inventory
And to put a Negative amount in the Out-of-Stock Threshold area (as suggested here (https://docs.magento.com/m2/ce/user_guide/catalog/inventory-backorders.html)
Now here how the product looks like now:
But when trying to ship the order after this configuration is done, I have now another error message:
Not all of your products are available in the requested quantity.
Already spent few days searching, modifying the configuration.... but still I'm not able to ship the order.
Note that when a configurable product has stock in real, I can ship. It is only when stock is 0 with backorder on that I can't ship the order.
Any help would be great.
PS: I was before testing that on Magento 2.3.0, and had the same issue.