Backend problem

[Plutocrat]

I don't really understand the problem here either. But here are a few comments. 

 - Ubuntu's four year limit. Don't understand this. You're not stuck to 14.04. You can upgrade at any time. Four years is when support stops, but upgrades are free. (Google Ubuntu Distribution Upgrade). Also, installing say 16.04 on a new box, and copying the /home/directory over to it usually works pretty well.

 - As far as I can see we're only talking about the data files. I don't think 32 bit vs 64 bit should make a difference to those. (correct me if I'm wrong). As long as you're backing up the data files, then sure, you've got all your data. 

 - If the problem is to do with opening the files on a Windows drive mounted in Linux, check the directory permissions. Gnucash will need write permission as well, to create a lock file (as well as save changes) so perhaps it can't create the lock file? Start with "Everyone can read, write, delete files" and narrow it down from there. 

P.