A few days ago I upgraded to WP 3.1.2, and also upgraded my WP e-commerce plugin to 3.8.3, and since then I've been spending countless hours putting my whole store back together since nearly everything broke.
All the products (though there are only 45) came lost their categories and other issues had to be fixed and tweaked.
I am using the dkret3 theme which I've customized a bit. It's been a few years since I originally built the store so I don't even remember half of the customizations I made, yet I do have everything backed up.
Now WordPress is nagging me to update the theme. I'm currently on v3.3 of dkret3 and the new version is 4.5. I am noticing that several widgets with the theme no longer work like they should so I guess it would be best if I did the upgrade, but I'm really not looking forward to spending more sleepless nights fixing everything again.
What is the least painful way to do this? Forgive me if this is a newbie type question but I don't want to take any chances. Is there some documentation or that will make it easier?