What causes this issue?

You deleted the shipment stage while the tender status was active. In
this way, the tender becomes invalid and the tender status is reset to
"Not offerred".

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?

First create new shipment stages and then set the tender status again.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.