Caution: You are about to change the exchange rate type or value date

What causes this issue?

You want to change the exchange rate type or the value date. This
change is critical if planning data for this version and/or actual cost
allocations have been written. In this case, you should not make any
changes because this can lead to inconsistent values in the data base.

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?

If the above-described data does not yet exist, you can ignore this
warning.
If such data already exists, you should not make any changes.
Otherwise, you would have to repeat all plannings, plan allocations and
possibly also actual cost allocations.

Error message extract from SAP system. Copyright SAP SE.