You are changing the planning parameters of &

What causes this issue?

You want to change the specified planning parameters. However these
have been created by &V2&. User &V1& was the last user to change the
planning parameters.

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?

Inform one of the two users that you want to make a change, or
Disregard this warning and change the planning parameters yourself.

Error message extract from SAP system. Copyright SAP SE.