Joomla 4.0.2 addresses a bug that was introduced into the Joomla Update Component (com_joomlaupdate package), breaking updates starting from 4.0.1
If you have already updated to 4.0.1 you will need to install this Joomla Update Component update, to fix the updater issue before you can update to 4.0.2.
More details you can find in the documentation: Update from 4.0.1 to 4.0.2.
Visit GitHub for the full list of bug fixes
Do you want to try Joomla 4.0 without migrating one of your sites?
Test it directly at: