The way you downgrade a firewall from PAN-OS 9.1 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
9.1 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.