Future price is zero ("valid from" date will be reset)

What causes this issue?

When you change the price unit, all the material's prices will be
recalculated.

System Response

Since the new price unit gives a future price with the value zero, the
"Valid from" date of the future price will be reset when you press
Enter.

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.