Change of conversion group changes the product type

What causes this issue?

You attempt to change the conversion group of the material. The product
types of the old and new conversion group are different.

System Response

The system issues this warning message. You can continue processing.

How to fix this error?

Make sure that the change of the conversion group makes sense.
Example:
A change from product type 2 "Oil products (gasoline, diesel, etc.)" to
5 "Asphalt" may be meaningful, since with release 4.6B new conversion
groups for asphalt have been delivered.
A change from product type 1 "Crude oil" to product type 6 "Natural
gas" does not appear to make any sense and may lead to errors when
goods movements are posted.

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.