Delivery status does not allow change in route

What causes this issue?

The route cannot be changed. The reason may be that the delivery already
contains a status that prohibits changes (for example, goods issue
already posted) or that the determination indicator set for the route
does not allow changes.

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 delivery has a status that prohibits changes to the
route.
Check the determination indicator for the route. By resetting this
indicator, it may be possible to enable the route to be changed again.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.