What causes this issue?

For tax reasons, the system only determines a taxable person when
settling a contract.
The system does not, for example, settle the contract for a product
change in the same way as for a surrender. No monetary benefits are paid
to the policyholder; instead capital is only transferred to another
product in the same policy. This information does not have to be
forwarded to the tax authorities. Therefore, a taxable person does not
need to be determined.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.