Every .aup file going back years, including new files, generates this error message. I tried to uninstall, searching for elements it didn’t uninstall, deleting them and re-installing the newest version, 3.2.4. I did a quick recording test, closed it and reopened it, and it reopened without error, and then when I tried to open it a bit later, I got this error again, and like i say, on every file I’ve tried to open. More info was not available, but I did hit ‘send’ on several of them.
I have a few old AUP projects around still - and all of those open fine on W10 with 3.2.4 and with the latest alpha test build I have for the upcoming 3.3.0 And just now I was able to create an AUP project with Audacity 1.2.6 and then successfully open it in 3.2.4