After switching to the DHL Retoure core integration, you have to link the new return shipping provider in the OTTO assistant. If the link is missing, the shipping confirmation fails even though the return label exists.

Error message

The log of the integration Plenty\Modules\Otto\Order\Services\SendShippingConfirmationService shows:

• module_otto::order.shipping.noShipmentsBuild with the message Es wurden keine Sendungen gebaut.
• The return package and shipping package do not contain a valid return tracking number.

How to fix the error

1. Open Setup » Assistants » Omni-Channel » OTTO basic settings » Return shipping providers and link all fields there. Check in particular that the new DHL entry is linked to DHL.
2. Under Data & Plugins » Plugins » Plugin set overview, check whether the old DHL Retoure Online plugin is still active. If so, deactivate it.
3. Open Orders & Fulfilment » Shipping centre and search for the order. In the Return labels tab, check whether a return label exists for every package number. If only the normal shipment is stored, the return label is missing.
4. Register returns with DHL via a flow that uses the flow action Register return with DHL. Event actions no longer work for this purpose.
5. Then trigger the shipping confirmation to OTTO again. The return label must exist before the shipping confirmation.