How To Fix UCF2021 - &1 is not within the customer namespace

SAP Error Message - Details

• Message type: E = Error

• Message class: UCF2 - Messages for Currency Translation

• Message number: 021

• Message text: &1 is not within the customer namespace

What causes this issue?

A specific namespace is reserved for custom settings for currency
translation (translation key, translation timeframe, translation
procedure, exchange rate period used, and procedure for exchange rate
determination). The settings delivered by SAP start with a numeric digit
, whereas customer settings start with an alphabetic character (letter).
The value you selected (&V1&) is not in the customer namespace.

System Response

The setting &V1& cannot be created, changed, or deleted.

How to fix this error?

Either call up input help and select an existing setting, or create a
new value in the customer namespace.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.