Selected fraction(s) are still assigned to an internal fraction

What causes this issue?

One of the selected partner fractions is still assigned to an
internal fraction in REA Customizing.

System Response

The partner fraction cannot be deleted.

How to fix this error?

Choose <DS:TRAN.J7LIZRF>REA Information Systems -> Assignment ->
Recycling Partner to -> Fraction</> to identify and delete the
<DS:TRAN.J7LO>REA Customizing entries</>.

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.