UPGRADE FROM 2.2 to 2.3

Dependencies

You'll need to follow the dependencies upgrade instructions.

Templates

standard_layout.html.twig has been updated (refactored layout accordingly to the theme). Some blocks have been moved, and the sonata_side_nav twig block became the main menu.
Admin's sidemenus are now tab-menus; former tab-menus are now collapsible items.

Admin classes

configureSideMenu and buildSideMenu methods of the Admin class have been deprecated; they are replaced by configureTabMenu and buildTabMenu.

Remove configureShowField

configureShowField has been deprecated since a while now, use configureShowFields instead => add a s.