Update to Billing plan not successful. Error received in save process.

What causes this issue?

During the posting of the changes to the Billing Plan for the sales
order, an error occurred that prevents the successful update of the
order.

System Response

This message is displayed indicating an error was received during the
save process. The error triggering the update failure is also displayed
in the resulting pop-up box.

How to fix this error?

Correct the issue identified in the additional error messages shown in
the message display and try posting the changes again.

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.