I did a little test, cloned my active boot configuration (SCALE 22.12.4.1) and set the clone as active, then rebooted. After that was working I switched trains and let her rip. The upgrade seemed to go smoothly.
What issues did I face?
My pool was not online. I had to carefully export it and then import it, that resolved the initial issue.
I noticed my Network report was in alarm condition, yet my network connection was working. The error was [Errno 2] No such file or directory: 'rrdtool'
even after a reboot. And of course this applied to all charts as well.
Then I thought, let's upgrade from 23.10-RC1 and see what happens. In RC1 I still have the 'rddtool' error message to start with.
After the upgrade I have the exact same problems.
To be honest, not a smooth upgrade if your pool is not available after the upgrade. If you are not careful you could destroy your pool when you export it. To me this signifies a huge risk.
Now to come clean about my configuration which may play a part in the issues I faced.
I am running on ESXi 7.0 U3 but I don't feel this is the issue.
My pool was created way back when running FreeNAS and I have not rebuilt it nor upgraded any ZFS features in roughly 6 years. I really shouldn't have to completely rebuild my NAS pools nor update the ZFS feature set but it may be a contributor to the problems.
My errors are completely repeatable, on my system.
I know others have witnessed several errors as well.
I did not do any further testing of anything else.
My cautionary tail here is to Not upgrade your ZFS Features so you have the option to roll back to your previous version, and I did successfully rolled back to 22.12.4.1 and all is good in the world. If all works well for you, I'd still wait on the ZFS Feature Set update if there are new features that would benefit you and I'd still wait a good month before updating just to make sure the software is working properly.
For those of you who had a great experience, I'm happy for you, but I need to wait for the next release I guess.