First of all, you really need to read this manual. I have never do, that’s why I never get my wordpress automatic updates work for me. As long as I see the new version on top of the dashboard, I will click on update now and end up in frustration because it just hanging there and no result or error messages. And I will go back to the normal manual upgrading.
Now, to make the auto upgrade works, just disable all your plugins, hit the upgrade wordpress button. You will get your blog updated to latest version and don’t forget to activate the plugins back.