Factory calendar & is not valid

What causes this issue?

During delivery and transportation scheduling while the system
attempted to determine a date, it came across a factory calendar
identification that is invalid or does not exist. The identification is
&V1&.

System Response

Scheduling is terminated. All dates are set to the start date for
scheduling.

How to fix this error?

Two calendars are involved for delivery and transportation scheduling:
The calendar defined for the shipping point and the one defined for the
route.
Check whether calendar identifications exist and whether they have a
valid value.

Error message extract from SAP system. Copyright SAP SE.