Inadmissable characteristic &2 for distribution (currency base for &1).

What causes this issue?

You have set a currency-bearing characteristic for distribution. The
characteristic value of this characteristic determines the currency or
unit for a key figure.

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?

Currency/unit conversions for top-down distribution are not supported
for this Release. Correct the entries either at key figure selection or
when selecting the characteristics to be distributed.

Error message extract from SAP system. Copyright SAP SE.