IDoc & was saved but cannot or should not be sent

What causes this issue?

IDoc &v1& stored in database. It was not sent because an error
occurred.

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?

Please check in the display whether an error occurred and make
appropriate changes to the IDoc as necessary.
IF &DEVICE&='SCREEN'
<ds:TRAN.WE02>Execute function</>
ENDIF

Error message extract from SAP system. Copyright SAP SE.