There is more than one active payment scheme for contract &1 on &2

What causes this issue?

During current processing, the system has determined that more than one
active payment scheme exists on &V2& for contract &V1&. This leads to
data inconsistencies.

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

System Response

Program termination (if necessary, with a short dump)

How to fix this error?

Note the message, the data and entries that lead to this error.
Create a problem message for SAP.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.