Forgot to add: after *saving* the xxxx.tax2020 for the very first time to the Downloads, I could easily use Windows Explorer to copy it over to the Tax folder ( for the first time ) where I intended to store it (and Where Turbo Tax defaulted to ) . However any subsequent attempt to overwrite it had an error.
That tells me the problem is the the permissions for the Folder, I think one of the previous people mentioned a new Windows 10 Folder security option.
In the meantime, the workaround seems to be to save it to the Downloads folder and copy it into your working directory when you are finished updating.
BUG - not a feature, but in this case the blamee is Intuit, who didnt test this out and make sure you can save it.
