Linux users of the Ubuntu 18.04 LTS (Long Term Support) are still waiting to upgrade their systems to 20.04. Normally at around the time the first point release of the new LTS distribution is released.
What is a point release?
These point releases include support for new hardware as well as rolling up all the updates published in that series to date. So a fresh install of a point release will work on newer hardware and will also not require a big download of additional updates. These include security updates and corrections for other high-impact bugs, with a focus on maintaining stability and compatibility with Ubuntu 20.04 LTS.
And 20.04.1 was released on August 6. But the problem is: not all flaws have been ironed out yet in 20.04.1. So at the moment you can’t be confident to get a smooth upgrade from 18.04 LTS. That’s why the upgrade is not yet available. Yes you can get a smooth install, but not a smooth upgrade.
Upgrade blocking bugs for 20.04
There are 2 blocking issues at the moment, and they must be solved first:
eoan to focal upgrade hangs when lvm snapshot is present(bug 1876506) resolved- grub-pc upgrade support (bug 1891680)
Here you can track the release status.
If you wanna take the risk, you can always force a upgrade with:
do-release-upgrade -d
December 8th, 2020 at 11:00 am
Upgrade to 20.04 is available since around 1st October 2020