No procurement variant exists for unit of measure &

What causes this issue?

You want to change the sales unit for a generic article with logistical
variants. A procurement variant already exists for the new sales unit.

System Response

It is not possible to change the sales unit. This is because only one
sales variant can match the sales unit.

How to fix this error?

You can define a new sales unit for the generic article and indicate
that it is the sales unit.

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.