Cannot upgrade to 17.04 - has gpg key changed?
116445
"Can't check signature: public key not found" while upgrading, why?
23819
"GPG error: Release: The following signatures were invalid: BADSIG"
65808
17.10 to 18.04 upgrade freezes during boot
149984
Can't update or install anything. Ubuntu 3.11.0.14
59088
How to upgrade to a newer release of Ubuntu using the Live CD?
144507
No facility exists in Update Manager to upgrade to a new version, why?
19288
Update manager doesn't offer an upgrade to the new release
75380
upgrading glibc to a version at least 2.17 or higher in ubuntu 12.04 LTS?
130374
Error saying "unable to update ICE authority" while booting
80899
"no public key available" on apt-get update
52647
How can I install npm on 17.10?
151605
upgrading from 15.10 to 16.04 apt not installed
103929
sudo apt upgrade error 18.04 (Broken Packages)
110148
Why does `do-release-upgrade` skip a version?
6833
Why is my Ubuntu 18.04 distribution asking me to upgrade to Pop!_OS 19.10?
9901
How to upgrade from 18.10 to 19.10, using the command line?
112955
How can I upgrade Ubuntu from 19.10 to 20.04 without losing packages?