This error comes when the weight of one or more products is not within the valid range of weight for your carrier.
The valid weight interval is 10g to 1000kg.
You will only get this error when you have filled out a wrong weight for a shipping method that requires a weight.
You will not receive this error if the shipping method does not require a weight and you haven't filled out the weight either.
To fix this you need to change the weight of the products specified in the error message, so they match the requirements from your carrier.