BADI: You are not allowed to change the field content of &

What causes this issue?

The contents of field &V1& have been changed in
<DS:GLOS.5C733369F735D311AE620060B03C9BBE>BAdI</> <LS>MB_MIGO_BADI</>
(method <LS>LINE_MODIFY</>). The changes, however, are only valid for
fields that are represented on a
<DS:GLOS.3526B1E1AFAB52B9E10000009B38F974>screen</> in transaction
MIGO.
The other fields of structure <LS>LSGOITEM</> provide internal control.
No changes are made to these fields.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.