Hi @informaticval and @michal_rames
As it is pointed in our wiki, Joomla! update process does not work properly from the "Joomla! Update" section. More info here. Later, the guide describes the necessary steps to upgrade it using the extension manager.
Have you tried those steps? If you are running into issues following them, could you please provide us the following information in order to try to reproduce your issue?
- What Joomla! version are you using?