its important to disable Qos and path selection before the upgrade (if I remember our upgrade to 9.2, it's just a couple of cli commands if I recall correctly).
Upgrade the device then push policies to restore the Qos and/or path selection Configuration.
A note of warning - in the lab we omitted the commands to disable Qos on a couple of steelheads before upgrading. We then had to delete the resulting corrupted config and manually copy/paste the correct updated Qos config from a successfully upgraded device. Not recommended!
Personally,I took it to mean a batch at a time as we have too many to do in one hit (take this advice at your own risk)
Get your core devices successfully upgraded, and their policies pushed, then the batch of posts upgraded and push the policies to that batch.