W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://prod-cdn.packages.k8s.io/repositories/isv:/kubernetes:/core:/stable:/v1.31/deb  InRelease: The following signatures were invalid: EXPKEYSIG 234654DA9A296436 isv:kubernetes OBS Project <isv:[email protected]>
W: Failed to fetch https://pkgs.k8s.io/core:/stable:/v1.31/deb/InRelease  The following signatures were invalid: EXPKEYSIG 234654DA9A296436 isv:kubernetes OBS Project <isv:[email protected]>
W: Some index files failed to download. They have been ignored, or old ones used instead.

tree /etc/apt/ -L 1
# /etc/apt/
# ├── apt.conf.d
# ├── auth.conf.d
# ├── keyrings
# ├── preferences.d
# ├── sources.list
# ├── sources.list.d
# ├── sources.list.distUpgrade
# ├── trusted.gpg.d
# └── trusted.gpg~

# 7 directories, 3 files

ls /etc/apt/sources.list.d
# docker.list.distUpgrade                               kubernetes.list                  ubuntu-esm-infra.sources
# gns3-ubuntu-ppa-lunar.list.distUpgrade                microsoft-edge.list              ubuntu.sources
# gns3-ubuntu-ppa-lunar.sources                         microsoft-prod.list.distUpgrade  vscode.list.distUpgrade
# graphics-drivers-ubuntu-ppa-kinetic.list.distUpgrade  microsoft-prod.sources           vscode.sources
# graphics-drivers-ubuntu-ppa-kinetic.sources           tailscale.list.distUpgrade       yarn.list.distUpgrade
# graphics-drivers-ubuntu-ppa-noble.sources             third-party.sources              yarn.sources
# helm-stable-debian.list                               ubuntu-esm-apps.sources
cat /etc/apt/sources.list.d/kubernetes.list
# deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.31/deb/ /

sudo rm /etc/apt/keyrings/kubernetes-apt-keyring.gpg

curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.31/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
sudo chmod 644 /etc/apt/keyrings/kubernetes-apt-keyring.gpg # allow unprivileged APT programs to read this keyring

sudo apt-get update
# Hit:1 https://packages.microsoft.com/repos/edge stable InRelease
# Hit:3 http://security.ubuntu.com/ubuntu noble-security InRelease
# Hit:4 http://kr.archive.ubuntu.com/ubuntu noble InRelease
# Hit:5 https://baltocdn.com/helm/stable/debian all InRelease
# Hit:2 https://prod-cdn.packages.k8s.io/repositories/isv:/kubernetes:/core:/stable:/v1.31/deb  InRelease
# Hit:6 http://kr.archive.ubuntu.com/ubuntu noble-updates InRelease
# Hit:7 https://esm.ubuntu.com/apps/ubuntu noble-apps-security InRelease
# Hit:8 http://kr.archive.ubuntu.com/ubuntu noble-backports InRelease
# Hit:9 https://ppa.launchpadcontent.net/graphics-drivers/ppa/ubuntu noble InRelease
# Hit:10 https://esm.ubuntu.com/apps/ubuntu noble-apps-updates InRelease
# Hit:11 https://esm.ubuntu.com/infra/ubuntu noble-infra-security InRelease
# Hit:12 https://esm.ubuntu.com/infra/ubuntu noble-infra-updates InRelease
# Reading package lists... Done
sudo apt-get upgrade
# Reading package lists... Done
# Building dependency tree... Done
# Reading state information... Done
# Calculating upgrade... Done
# The following upgrades have been deferred due to phasing:
#   file-roller python3-distupgrade shotwell shotwell-common ubuntu-release-upgrader-core ubuntu-release-upgrader-gtk
# 0 upgraded, 0 newly installed, 0 to remove and 6 not upgraded.

sudo apt-key list
# Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).
# /etc/apt/trusted.gpg
# --------------------
# pub   rsa2048 2022-08-25 [SC] [expires: 2026-12-29]
#       DE15 B144 86CD 377B 9E87  6E1A 2346 54DA 9A29 6436
# uid           [ unknown] isv:kubernetes OBS Project <isv:[email protected]>