The way you downgrade a firewall from PAN-OS 9.0 depends
on whether you are downgrading to a previous feature release (where
the first or second digit in the PAN-OS version changes, for example,
from 8.1.2 to 8.0.13 or from 8.0.6 to 7.1.9) or downgrading to a
maintenance release version within the same feature release (where the
third digit in the release version changes, for example, from 8.1.2
to 8.1.0). When you downgrade from one feature release to an earlier
feature release, you can migrate the configuration from the later
release to accommodate new features. To migrate the PAN-OS 9.0 configuration
to an earlier PAN-OS release, first restore the configuration for the
feature release to which you are downgrading. You do not need to
restore the configuration when you downgrade from one maintenance
release to another within the same feature release.
Always downgrade into a configuration
that matches the software version. Unmatched software versions and
configurations can result in failed downgrades or force the system
into maintenance mode. This only applies to a downgrade from one
feature release to another (for example 9.0.0 to 8.1.3), not to
downgrades to maintenance releases within the same feature release
version (for example, 8.1.3 to 8.1.1).
If you have a problem
with a downgrade, you may need to enter maintenance mode and reset
the device to factory default and then restore the configuration
from the original config file that was exported prior to the upgrade.