Employment change would lead to an unallowed further personnel number.

What causes this issue?

The replicated employment information reflects a change which would lead
to the creation of a further personnel number for the same employment.
This contradicts to the usage of the assignment ID external for the
personnel number as configured by switch SFEC PERNR equal to value 1 in
customizing table T77S0. Using the assignment ID external basically
requires a one to one relationship between an employment and the
personnel number.

System Response

No further personnel number can be created.

How to fix this error?

Correct the issue causing employment information change in Employee
Central.
In case of an intended inter-company transfer it is strongly recommended
to terminate the existing employment and to use the functionality
"Rehire with New Employment".

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.