Maciej, please have a look at this topic
http://www.oxwall.org/forum/topic/21778.
It
would be better not to wait for so long time to update your software.
In your case we can not guarantee the correct update of the software and
the functionality. So, before you attempt to update, make sure that
you:
- Make back up of your website;
- Run the platform update first, till updating all available plugins;
- Run theme update also only after the platform update.