The error (An Error Occurred when trying to Create Shipment - ErrorMessage: Error Occurred details: Error Code:1015 Obj:consignment.totalWeight Error Type:Validation Error Message:Maximum value exceeded) from DPD typically occurs when the product weight has too many decimal places.
To resolve this issue please review the steps below:
Edit product weights
Round the weight of each product to one decimal place. For example, change 1.020 to 1.0.
Go to Products then Overview.
Search for the product.
Click Actions then Edit.
Click the Pricing & Size tab.
Edit the Weight field.
Click Save.
Repeat steps 2-6 for additional products.
Recalculate order weight
After updating product weights, you'll need to recalculate the order weight.
Go to Orders then Overview.
Find your order.
Open the Bulk Actions drop-down and search for Recalculate Order Weight.
Select the tick box next to the order.
Click Go.
Check for items without weight
If you still can't create the shipment, check if any items have no weight assigned.
Review each item in the order for missing weight values.
If an item has no weight, turn on the Packaging toggle for that item.
Note: DPD will reject shipments containing items without weight values.