$ sudo do-release-upgrade -c # It SHOULD work as 22.04 is released now
Checking for a new Ubuntu release
No new release found.
$ sudo do-release-upgrade -d # This is the only solution now which is abnormal
Checking for a new Ubuntu release
= Welcome to the Ubuntu 'Jammy Jellyfish' development release =
''This release is still in development.''
............
当前的镜像是archive.ubuntu.com. 当前的操作系统是21.10.