There are attendances or absences during the temporary assignment period

What causes this issue?

You want to delgate employee &v3& in the period from &v1& to &v2&.
However, there are absences or attendances for employee &v1& in this
period.

System Response

Because of the existing data records, you cannot enter the delegation
from &v1& to &v2&.

How to fix this error?

First, delete the existing absences or attendances for employee &v3& in
the period from &v1& to &v2&, or change the delegation period so that
no absences or attendances are affected.

Error message extract from SAP system. Copyright SAP SE.