&1: Conversion from &2 to &3 to &4 during set up is not possible

What causes this issue?

The revaluation of the key figure &V1& of unit &V2& to &V3& for event
&V4& is not possible for the new set up, because the parameter INITIAL
is needed for the revlauation.

How to fix this error?

As long as the source field is not filled when setting up, no error
occurs. If the source text is filled, however, or if various values are
calculated with a formula, the revaltuation with initial parameters
leads to a cancellation of the posting.

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.