You do not have change authorization for group &

What causes this issue?

This error message might be due to the following reasons:
You have tried to change planning parameters for which authorization
group &V1& is defined.
You have tried to assign authorization group &V1& to the planning
parameters. You do not have authorization for this group.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

System Response

The authorization object for planning parameters is called G_820_GPL
and is made up of the authorization group and the activity, which has
the value 02 for change authorization.

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.