I would check with Customer Support. There was a thread in the Kobo section of people having problems downloading epubs which was due to a server problem on the Kobo end. Kobo supposedly got it fixed, but there have still been a trickle of reports of people still having sporadic issues. That's more likely the problem than ending Sony support.
See this thread:
https://www.mobileread.com/forums/sh...d.php?t=321751