&1 check Customizing for external infostructure

What causes this issue?

No info structure has been defined for the external document data
and/or the period grid is not specified.

System Response

The system can not continue processing.

How to fix this error?

In general REA Customizing under "Control of Declaration/Origin of
Movement Data", please maintain the external infostructure and the
period grid. The only external infostructure allowed is J_7LS990.
Restart the program again directly afterward.

Error message extract from SAP system. Copyright SAP SE.