This is a great post. However it is mistaken that the recommended steps are to download and install the major.minor.0 version. There used to be a KB article which appeared to suggest this without careful reading but it's not the case. The current docs are clearer that after additional maintenance fixes are released you should download but not install the major.minor.0, download the target major.minor.x release, then install the target release. Of course, there could be other reasons you were given advice otherwise.
> So the official upgrade path is to download and install the .0 version in the chain (e.g. 10.1.0). Then, after rebooting, download and install the .x version (e.g. 10.1.5).
Supporting document: https://docs.paloaltonetworks.com/pan-os/10-1/pan-os-upgrade/upgrade-pan-os/upgrade-the-firewall-pan-os/determine-the-upgrade-path
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