3rd and (final for now) comment -- the "system reports" program handles smaller screen sizes very poorly -- both may start off with an unusably-large window (offscreen in all dimentions), and the minimum vertical height is problematical too. I can see this being a real issue for some netbook users and similar.
Update-manager issue could be 'worked around' by right-clicking on update-manager icon and finding 'refresh' that way (that button not disabled), BUT I still think the "update manager needs an update" state should allow you to (a) "Refresh" the update list and (b) "switch mirror" if you are stuck pointing to a broken mirror where you can't download update-manager from...
I note, running in recent Virtualbox [e.g. 6.1.8 debian package], in VMSVGA mode (the only type apparently supporting 3d acceleration), desktop rezing does not work!. This is fixed by manually installing the 'guest additions' afterwards, but I thought Linux is supposed to have better driver/support out of the box. There should at least be a release-note somewhere explaining how to make this config work (and have 3d acceleration working too for that matter), preferably better out-of-the-box experience included in mint 20.
After install, update manager now stuck in a state where it is insisting that must first install an update to update-manager (even if restarted, won't let you 'refresh'...
BUT -- also unable to do so -- failing to fetch http://packages.linuxmint.com/pool/main/m/mintupdate/mintupdate_5.6.7_all.deb -- 404 Not Found [IP: 188.8.131.52 80]
My issues with the Bluetooth icon & Open as Root are indeed fixed, thanks!
cpatrick: Try compatibility mode.
Test #20 error message http://imgur.com/a/7dxn57s