So I experimented a bit and tried Will's suggestion - the upgrade from 9.10.1 to 9.10.2 went smoothly, no errors. But then going from 9.10.2 to 9.11.2 still hit the same snag on the Persona Bar Extensions. 

I had found this article on the DNN Corp support site: https://dnnsupport.dnnsof...ter-a-failed-upgrade  and used the recommended technique to restart a failed upgrade after downloading and replacing 2 the install files (install.aspx and DotNetNuke.install.config.resources) and launching install in a special mode. That caused the ugrade to relaunch and finish almost immediately, and the only items listed in the onscreen progress report was jQueryMigrate and jQueryUI.  Checking the install logs, I also see that same pair tacked onto the end of the file started with my original upgrade, InstallerLog20230522.resources.  However, there it also shows a few additional steps, adding a couple Telerik Removal pages and adding a module to that page (see below).

I forgot to change the customErrors in the web.config to be able to see what the real error was, prior to the install. 

After the restarted upgrade finished, View Your Site worked fine, and I did not see the PersonaBarExtension in the "Available Extensions" this time, only in the installed extensions. 

So not sure if I'm golden yet. I may run it one more time with the customErrors off to let me view that error right when it happens. Or I could just wait for 9.11.3 as Will suggests! :)

Thanks! David

One thing... Do you have any non-core scheduler tasks?  Regardless, you may want to turn off the scheduler before attempting any upgrades, then turn it back on after all upgrade steps are completed.  This is something we do by process (and habit) now too.  

Thanks Will - definitely worth taking those simple steps as a precaution in any case. As I'm working through a set of about 8 different sites, I've actually had a couple complete with no errors at all.