An abbreviated path is better, but is it necessary at all for a brand new installation with no data having been loaded in the ZD? Couldn't we just go straight to 188.8.131.52.15, or whatever the newest version is at the time and load data from there forward?
No you do not need to following all the steps. It depends on what version of software is present on your ZD and accordingly you can follow a step by step upgrade path (can be found in the Release notes) to upgrade to the latest version. For instance, if your ZD was on 184.108.40.206.50 or 220.127.116.11.15 etc then you could have directly upgraded to 18.104.22.168.15. However, if your ZD was on 22.214.171.124.8 then you have to again follow an upgrade path and you cannot go straight to 126.96.36.199.15. It's always a good step to check with our Support team or use our Support Forums before you want to do a software upgrade if you have any doubts :)
Here is some data around upgrade/downgrade rules: A bit developer terminology but should give better clarity:
ZD upgrade and downgrade rules are as following:
1. About ZD upgrade:
a. ZD didn’t support any version upgrade to any version, ZD only support upgrade to some version from other version which is defined in “controller/ac/REQUIRE_VERSIONS” in this new branch.
(Generally, ZD support two version upgrade. For example, 9.1/9.2 can upgrade to 9.3, 9.2/9.3 can upgrade to 9.4, 9.3/9.4 can upgrade to 9.5. but some small version can’t support. )
For example in 188.8.131.52, it define: 184.108.40.206 220.127.116.11 18.104.22.168 22.214.171.124 126.96.36.199 188.8.131.52 in “controller/ac/REQUIRE_VERSIONS”, so only those version can supported to upgrade to 184.108.40.206.
b. When upgrade, ZD will do the migration process.
If ZD can match the whole old version to current version in ZD’s etc/migration. It will do the process in it. Otherwise, it will match the front two version number.
For example, if we upgrade 220.127.116.11 to 18.104.22.168, ZD will do migration in 22.214.171.124-126.96.36.199/db_upg, if we didn’t build 188.8.131.52-184.108.40.206 in ZD’s image, ZD will do migration in 220.127.116.11-18.104.22.168/db_upg.
2. About ZD downgrade:
a. If ZD upgrade from one old version to new version, then downgrade to the old version, ZD can use the old version’s configuration or set factory.
b. If ZD downgrade to other version, ZD only can chose set factory, and now ZD can downgrade to any version, and no limit.