The latest versions of Joomla agree to upgrade the package joomla as if it were a normal part via "Check for updates".
Very often, however, there appears the following error message:
The PHP setting allow_url_fopen is disabled. This setting must be enabled because the updater function.

This message is due to settings of the server hosting the site that you want to upgrade. To overcome this problem there are several solutions:

• The first is to set on the server the value of allow_url_fopen = On asking your provider to make this change. This choice is often not easy because for security many providers do not change.
• The second option is to set it through. Htaccess file by adding the following line of code: php_value allow_url_fopen On
• The third option requires you mentioned if the other 2 have not been successful. This choice is simply to upgrade as in older versions of Joomla, that is, download the update packages and upload files to your server via FTP.