Hi,
Like Lionel said, I never ever harry to upgrade Joomla. This is vital. How can the developers of the other extensions of Joomla, like SEBLOD know what is the new version of Joomla surprise them with. No mater how close to the Joomla project you are, you can be never certain of the out come, after an update.
So, what is the conclusion, like Lionel said: never update your Joomla before you are sure at least the major components that drive your site as SEBLOD are up to date with the current version of Joomla.
Best regards,
ricco