Cant Update Kodi from 15.2

Hello,

I am currently Running Kodi 15.2 and have been trying to upgrade without success for some time.

Yesterday I got brave and Installed V16 over the top with half the move database going missing. I restored it bnack to 15.2 and installed V17 over the top,again I lose half my database of movies. (To exactly the same spot it would seem making me think there is a fault in the database)

If I then try to update the database, i get doubles and movies missing, It is a nightmare with over 3500, movies in the database.
I also of course have my selected posters and artwork, and names of movies which means weeks of work if i am to rebuild the database again.

So here i sit at 15.2 afraid to update.

Any Ideas