What do for upgrade from ubuntu 19.04 to 20.04 and if don't work repository on 19.04
211
Can I skip over releases when upgrading?
63514
How do I decide what version of Ubuntu to install?
131474
How to only install updates from a specific repository?
74079
How to Upgrade Ubuntu 12.04.2, 12.04.3 to 12.04.4, the next Hardware Enablement Stack?
144172
How to upgrade to a point release from the same base release (12.04 to 12.04.03)
33651
How to upgrade from Ubuntu 12.10 to 14.04
64509
Can't update from official repositories [Error 409]
43778
Is it possible to "upgrade" from a 32bit to a 64bit installation?
110896
Package installation - Outdated repository
35243
Is it safe to do-release-upgrade from 12.04.4 to 14.04.1?
2136
How to roll back Ubuntu to a previous version?
60659
Install newer package version from trusty-backports
129101
Upgrading Ubuntu 9.04 to 9.10 when Update Manager doesn't let you
93942
How to fix "Failed to download repository information" error while updating?
31506
How do I update Ubuntu manually?
23096
How to remove obsolete packages after failed release upgrade via do-release-upgrade on Ubuntu?
10633
software updater failed to download repository information