Currency type &1(&3), source crcy type &2 has real time conv switched off

What causes this issue?

IF &V3& <> ' '
Company code &V3&:
ENDIF
For currency type &V1& the source currency type is &V2&. For currency
type &V2& the real time conversion is switched off. Currency types with
real time conversion switched off are not allowed to be used as source
currency types.

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?

Please use currency type with real time conversion switched on as source
currency type.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.