Had exact problem this morning. Tried install 2 times. Then decided to reload 16.09.39 file i had saved. i save all updates (just rename them for the # they have) just in case of problems like this.. I had loading problems with that version as well. So i uninstalled the game entirely (and took out my license as they suggested). And reinstalled the 16.09.39, entered my license, and the game ran. But i had a lot of problems saving back-ups. Got errors telling me my auto save feature wasn't working correctly. Ended up cutting an "auto-save" file from my C drive, and putting it in my F drive (back up external) and then re-pasting it back in my C drive folders when i was done ... back-ups worked perfectly then.
Then i noticed i didn't have any of my add-on central servers. had a heck of a time figured that one out, as Add a server wouldn't work. Finally i found a folder on my C drive for "add-ons" and i moved the temp.xml file to another folder, and then everything worked. When i moved it back to where it was, everything was still working. Go figure.
Anyway, after about 8 hours of fiddling and mostly cursing, i got the folders, files and game back to where it was before i tried to use the "new" updated file. i'll keep this where it's at until i get a copy of OOTP 17. Hopefully the import feature will be seamless.
Anywho ... just letting you know you're not alone in the new update not working. And you can go back to an older version, just be aware it might take some work. It shouldn't and i'm not certain why i had so many problems, but it's all good now here.
Good luck.