Field & does not have a preceding length field of type &

What causes this issue?

The table contains a long field (data type LCHR or LRAW), which does
not have a preceding length field. Long fields require a preceding
length field of type INT4.

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?

Include a length field of type INT4 in the table. It must be located
directly before the long field in the field list. Please also note that
long fields must be located at the very end of the field list.

Error message extract from SAP system. Copyright SAP SE.