Route determination found route &1 to be invalid

What causes this issue?

A route has been entered in the delivery which the route check deems to
be invalid. Either the route does not exist or, if it does, it is
invalid for the delivery.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Check whether the route entered exists as master data.
If the route entered exists as master data, check whether it is valid
for the products, quantities, date/time, locations, partners and other
restrictions.
If you want to check which restriction may be responsible for the fact
that a route is invalid for a delivery, choose <ZK>Extended Warehouse
Management -> Master Data </>-> <ZK>Shipping and Receiving</>-><ZK>
Route Determination -> Simulate Route Determination</> from the SAP Easy
Access screen and simulate the route determination.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.