Error while reading FFF subset &1

What causes this issue?

An internal error occurred while reading the FFF Subset.

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?

Check if the FFF Subset you are reading is valid
Contact your system administration

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.