EDI: The IDoc & does not contain any segments

What causes this issue?

Segments of IDoc &v1& are to be accessed during the syntax check for
IDocs.
But the IDoc does not contain any segments.

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?

Error message extract from SAP system. Copyright SAP SE.