No "off" shift in shift group &

What causes this issue?

You want to delegate an employee. However, since you have not entered a
shift yet, the system attempts to generate a "day off" shift. But this
is not possible, since a 'day off' shift does not exist in shift group
&v1& of &v2& &v3&. ('Day off' is defined as a daily work schedule with
daily work schedule class 0.)

System Response

You have to enter a shift abbreviation from shift group &v1&.

How to fix this error?

You have two options:
Enter a shift abbreviation from shift group &v1&.
See to it that a 'day off' shift is added to shift group&v1&.

Error message extract from SAP system. Copyright SAP SE.