Value & in set & has been transferred without change

What causes this issue?

Value &V1& occurs in set &V2& as
the from value of a set line,
the to value of a set line, or
the representative value of the set.
The value should be converted during the set conversion because
the attributes of the new reference field of the set stored in the
Dictionary differ from those of the old reference field
or because
a conversion exit is entered for the reference field of the set in the
field movement table for the conversion of FI-GLX tables.
However, the value conversion could not be performed because
for the value in the set, a corresponding value could not be found for
the new reference field, or
a conversion exit is specified for the reference field of the set in
the field movement table for the FI-GLX conversion, but there is no
corresponding FORM routine for this exit in the FORM pool RGUUX000.

System Response

The value is transferred without change.

How to fix this error?

If the entry for the conversion exit in the field movement table for
the FI-GLX conversion is incorrect, you should correct it and then
repeat the conversion.
If this is not the case and you do not want the set value to be
transferred without change, you can change the set as required once the
conversion is completed.

Error message extract from SAP system. Copyright SAP SE.