Menus and Cassiopeia Positions
Note the location of position 'menu'.
In Joomla! 3 the Main Menu might have been as say 'Position 7'. So the menu might not be showing after the upgrade to Joomla 4 as 'Position 7' is not defined.
See Notes later about changing the positionof the main menu
Many positions are shown opposite.
This example is for a multi language site. There are 4 'front end' languages: Arabic; German; French and English.
Note the misspelt Main Menu En as 'Mani Menu EN'.
The lowest set of frontend positions in Cassiopeia is shown opposite.
This includes positions:
bottom-a, bottom-b, footer and debug.
Changing Menu Position
In Content from the admin menu select 'Site Menus' as indicated opposite
Set the Search Field to Main Menu.
This will show a view such as opposite.
Note that the Position is 'position 7'.
Then select your target position for the Menu Module, which in this example is Sidebar-right.
The Main Menu will now appear in the 'sidebar-right' position.