Date & is before the valid factory calendar period

What causes this issue?

You entered a date for which the
<GL:factory_calendar>factory calendar</> was not maintained in
your factory.

System Response

INCLUDE 'KEINE-VERARBEITUNG' OBJECT DOKU ID TX LANGUAGE E

How to fix this error?

Enter a valid date.
If you want to use the date rejected by the system as a valid
date, you must maintain the factory calendar in your system with the
help of the Customizing function:
IF &DEVICE& = 'SCREEN'
<DS:TRAN.OY05>Proceed</>
ENDIF
INCLUDE 'DARF-NICHT' OBJECT DOKU ID TX LANGUAGE E

Error message extract from SAP system. Copyright SAP SE.