I tried that as well. Then I get errors from all the 3rd party extension (3PE). I was told that upgrading 3PEs was the first order of business. Then Joomla, then PHP. This seems the biggest problem with Joomla and I can see why many went to WordPress.
In fact, I am really hoping Seblod Army will make this component for WP. It's amazing in many ways, but Joomla seems like divergent mess at times. WP upgrades are a snap.
And if does not work, you will need to do in in multiple steps, so that you do not go directly to latest version - you first udate Joomla to some higher version than Seblod and so on until you reach latest versions of both. YOu will need to experiment a bit and proably also search in the release logs as sometimes new Seblod version was released for compatibility with certain Joomla version.