I deleted SupportAssist using an uninstaller and then reinstalled it from a link to the newest version that I was given. That resolved it.
I repeatedly get the message that a new version is available and will be installed on this PC, already for several months.  When I click "Yes, update now.", I immediately get the notification "We were unable to download a file for installation.  Check your internet connection and try again."  I know my internet connection is working.
New version will not download