Error when converting from & to &

What causes this issue?

An error occurred when converting from currency &V1& to currency &V2&.

System Response

An amount was not converted correctly.

How to fix this error?

Check that the settings for currency conversion have been made
correctly in the Implementation Guide.
Also check the current amounts (rates, base value) and, if necessary,
enter correct values manually.

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.