Apparently, Windows Defender can interfere with TurboTax being able to access folders. This is why the TT401 error occurs. It requires changing permissions in Windows Defender to allow TurboTax to save files.
The suggestions about saving to another device or re-installing by downloading from Intuit don't address the root cause of this problem and shame on Intuit for not mentioning this in this thread and others dealing with this issue.
