System cannot uniquely determine account assignment object &1

What causes this issue?

The system can<ZH>not</> uniquely determine account assignment object
&1.

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?

Select an object by choosing <ZK>Find</>, or use the input help. If it
is not possible to make an entry, the system has to be able to derive
the object (uniquely). However, this is not the case.
Check the entries in the basic data (contract or rental object).

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.