Personnel number & does not exist

What causes this issue?

You have specified a personnel number that has not been created in the
SAP <LS>Human Resources</> system.

System Response

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

How to fix this error?

Choose an existing personnel number.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.