Determine the upgrade path and upgrade your standalone,
HA, and Panorama-managed firewalls to PAN-OS 9.0.
How you upgrade to PAN-OS 9.0 depends on whether you
have standalone firewalls or firewalls in a high availability (HA)
configuration and, for either scenario, whether you use Panorama
to manage your firewalls. Review the PAN-OS 9.0 Release Notes and
then follow the procedure specific to your deployment:
Additionally, it is not recommended
to manage firewalls running a later maintenance release than Panorama
as this may result in features not working as expected. For example,
it is not recommended to manage firewalls running PAN-OS 9.0.2 or
later maintenance releases if Panorama is running PAN-OS 9.0.1.