https://www.ifixit.com/Answers/View/392378/Error+26+in+iTunes notes what I know today.

"There is no such thing. At this date, you cannot get data from a device that fails to update and throws errors 26."

There are folk that forgot to backup and this happens. They get very upset and it appears there is little you can do for them. Some run off and pay recovery houses yet, as of today, I have yet to find anyone that will guarantee recovery from this condition.

I'm now using Google Photos as an auto backup. I used to use Dropbox which was available on iPhone so with iTunes and many other options I think the old saying is still true. We only lose what we don't backup. This is why I opted for more automatic backups. That is, the moment I connect to WiFi which is automatic at home, my stuff is synced.