A by-product is unreceived the same way as the main product using Unreceive Shop Order page. The quantity needs to be available on the same location (and probably project) as when received.

Thank you Björn.

Seems like the Shop Order needs to be received before it’s possible to unreceive the By-Product.

When I tested and for me it works fine to receive and unreceive the by-product before I received the main product of the shop order.

Okay, I see. I, obviously, did not read your initial message carfully enough.

I was working directly from the Shop Order Header and there it was only possible to receive the By-Product at any time but the unreceive option will only present itself as a valid option once the Shop order is received.

Thanks again for your support!