Port '&' does not exist in the table of port descriptions

What causes this issue?

For port &v1&, IDocs should be transferred with an R/2 system. The port
no longer exists in the port description table.

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?

You should create this port or use an existing port.
IF &DEVICE&='SCREEN'
<DS:TRAN.WE21>Execute function</>
ENDIF

Error message extract from SAP system. Copyright SAP SE.