Select exactly one shipment

What causes this issue?

To execute this function, you need to select exactly one shipment
document.

System Response

The system terminates the process.

How to fix this error?

Select a shipment document and carry out the process 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.