Control record &2 not found when importing file &1.

What causes this issue?

When importing file &V1&, the system tried to read a control record for
structure &V2&.
This control record contains the structure of the stored data, along
with the number of records to be read. The system could not find this
control record.

System Response

Processing is not continued.

How to fix this error?

Check input file &V1&. If this file was created by a standard SAP
program, contact the SAP Hotline.

Error message extract from SAP system. Copyright SAP SE.