Upgrade Kubuntu 20.04 to latest release (21.04), instead of next release (20.10)

Question

I want to upgrade from Kubuntu 20.04 to 21.04.

I have changed /etc/update-manager/release-upgrades so that Prompt=normal.

Running pkexec do-release-upgrade -m desktop -f DistUpgradeViewKDE I get the option to upgrade to 21.10.

Also,

sudo do-release-upgrade -m desktop
[sudo] password for cip: 
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [819 B]                                                                                                                                    
Get:2 Upgrade tool [1 340 kB]                                                                                                                                           
Fetched 1 341 kB in 0s (0 B/s)                                                                                                                                          
authenticate 'groovy.tar.gz' against 'groovy.tar.gz.gpg' 
extracting 'groovy.tar.gz'

I guess that should say hirsute instead of groovy.

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How to upgrade to latest 21.04 directly?

Solution

There is no tested, supported upgrade path from 20.04 to 21.04.

You have three options:

1. Release-upgrade from 20.04 and 20.10, then again from 20.10 to 21.04.

2. Back up your data and clean-install 21.04.

3. Use the Debian dist-upgrade method. We do not test that method, nor provide support if you break your system using it, so I'm not going to explain it.

Mark your calendar: 21.04 will live for only 9 months. You are committing to upgrades every 6 months when you migrate to a non-LTS release. Do not miss the upgrade window.