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Upgrade Proxmox 8 to 9 Without Breaking Your Homelab

5 min read
How-to

Let’s get one thing out of the way:

Proxmox upgrades are not fragile.
People are.

Most guides assume:

  • nothing goes wrong
  • you don’t interrupt anything
  • you don’t get stuck in a pager
  • you don’t panic halfway

That’s not reality.

This guide is based on an actual upgrade — including:

  • interrupted upgrade
  • broken package state
  • lock issues
  • recovery

If you follow this, you’ll finish the upgrade even if things go sideways.

🧭 What This Covers

  • Proxmox VE 8 → 9
  • No-subscription repo
  • Single-node homelab (or small cluster)
  • GPU passthrough setups (Plex, etc.)
  • Recovery from broken upgrades

⚠️ Before You Start (Do Not Skip This)

1. Backup

If your backups are “probably fine”, they are not fine.

  • Backup all VMs and containers
  • Test restore if you’re serious

2. Upgrade to latest Proxmox 8 first

apt update
apt dist-upgrade

3. Run the upgrade checker

pve8to9 --full

You want:

  • ❌ 0 failures
  • ⚠️ warnings are acceptable
Proxmox upgrade pre-check summary

4. Disk space

df -h /

Minimum:

  • 5GB usable
  • 10GB preferred

Here is an example: 

root@pve2:~# df -h /
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/pve-root   94G   11G   79G  12% /

🛑 Stop Everything (Yes, Everything)

Before touching repositories:

From UI:

Node → Bulk Actions → Bulk Shutdown

This is not optional if you care about stability.

Bulk Shutdown option in Proxmox

Why?

Because during upgrade:

  • networking restarts
  • services reload
  • kernel changes

Running VMs during this:

  • can hang
  • can corrupt writes
  • can behave unpredictably

You gain nothing by keeping them running.

🚀 Phase 1 — Switch Repositories

1. Switch Debian to Trixie

sed -i 's/bookworm/trixie/g' /etc/apt/sources.list

2. Remove old Proxmox repo

rm /etc/apt/sources.list.d/pve-install-repo.list

3. Add Proxmox 9 repo (no-subscription)

cat > /etc/apt/sources.list.d/proxmox.sources << EOF
Types: deb
URIs: http://download.proxmox.com/debian/pve
Suites: trixie
Components: pve-no-subscription
Signed-By: /usr/share/keyrings/proxmox-archive-keyring.gpg
EOF

4. Remove Ceph repo (if unused)

rm /etc/apt/sources.list.d/ceph.list 2>/dev/null
rm /etc/apt/sources.list.d/ceph.sources 2>/dev/null

Here is how it should go as an example: 

root@pve2:~# sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
root@pve2:~# rm /etc/apt/sources.list.d/pve-install-repo.list
root@pve2:~# cat > /etc/apt/sources.list.d/proxmox.sources << EOF
Types: deb
URIs: http://download.proxmox.com/debian/pve
Suites: trixie
Components: pve-no-subscription
Signed-By: /usr/share/keyrings/proxmox-archive-keyring.gpg
EOF
root@pve2:~# rm /etc/apt/sources.list.d/ceph.list 2>/dev/null
rm /etc/apt/sources.list.d/ceph.sources 2>/dev/null
root@pve2:~#

5. Update

apt update

6. Verify

apt policy

You should NOT see:

  • ❌ bookworm

You SHOULD see:

  • ✅ trixie
  • ✅ pve-no-subscription

Example of the apt policy command:

Package files:
 100 /var/lib/dpkg/status
     release a=now
 500 http://download.proxmox.com/debian/pve trixie/pve-no-subscription amd64 Packages
     release o=Proxmox,a=stable,n=trixie,l=Proxmox Debian Repository,c=pve-no-subscription,b=amd64
     origin download.proxmox.com
 500 https://deb.nodesource.com/node_22.x nodistro/main amd64 Packages
     release o=. nodistro,a=nodistro,n=nodistro,l=. nodistro,c=main,b=amd64
     origin deb.nodesource.com
 500 http://security.debian.org/debian-security trixie-security/main amd64 Packages
     release v=13,o=Debian,a=stable-security,n=trixie-security,l=Debian-Security,c=main,b=amd64
     origin security.debian.org
 500 http://deb.debian.org/debian trixie-updates/main amd64 Packages
     release v=13-updates,o=Debian,a=stable-updates,n=trixie-updates,l=Debian,c=main,b=amd64
     origin deb.debian.org
 500 http://deb.debian.org/debian trixie/contrib amd64 Packages
     release v=13.4,o=Debian,a=stable,n=trixie,l=Debian,c=contrib,b=amd64
     origin deb.debian.org
 500 http://deb.debian.org/debian trixie/main amd64 Packages
     release v=13.4,o=Debian,a=stable,n=trixie,l=Debian,c=main,b=amd64
     origin deb.debian.org

🔥 Phase 2 — The Upgrade

apt dist-upgrade

This process may show you additional screens. For example the below screen you can either PG DN multiple times, to go to the end or simply press q

Linux terminal output about ping configuration.

⚠️ What Will Trip You Up

Pager screen

You’ll see: lines xx-xx (END)

Press: q

Git update notes: git-daemon security changes.

Config prompts

(Y/I/N/O/D/Z)

If unsure: → press Enter

You may see other screens like this below, just keep the local version if you are not sure:

Grub configuration options

💥 If You Interrupt the Upgrade

Recovery

ps aux | grep apt
kill -9 <PID>
dpkg --configure -a
apt -f install
apt dist-upgrade

Repeat until clean.

✅ Phase 3 — Finalization

Check version

pveversion

This command should output something like this below, note the version number is 9.x.x.

root@pve2:~# pveversion
pve-manager/9.1.7/16b139a017452f16 (running kernel: 6.8.12-20-pve)

Reboot

reboot

Or you can just click on the UI.

Reboot button in a Proxmox interface.

The reboot process will take some time. Once it is done, do not forget to force refresh your web access UI. (usually cmd+R or ctrl+R)

Proxmox Virtual Environment console

Confirm kernel

uname -r

⚠️ Important Change

/etc/sysctl.conf is no longer used

Move configs to: /etc/sysctl.d/

🔍 Post-Upgrade Checks

You should only do this if any of your VM is running plex and uses NVidia card passthrough.

GPU check

nvidia-smi

NVENC check

ffmpeg -encoders | grep nvenc

Real test

ffmpeg -f lavfi -i testsrc=duration=5:size=1280x720:rate=30 \
-c:v h264_nvenc -f null -

🧹 Cleanup

apt autoremove
apt modernize-sources

Example apt autoremove. Press Y to remove:

root@pve2:~# apt autoremove
REMOVING:                       
  libxenmisc4.17  proxmox-kernel-6.8.12-17-pve-signed

Summary:
  Upgrading: 0, Installing: 0, Removing: 2, Not Upgrading: 0
  Freed space: 579 MB

Continue? [Y/n] Y

Here is the example of apt modernize-sources. Press Y to continue.

root@pve2:~# apt modernize-sources

The following files need modernizing:
  - /etc/apt/sources.list
  - /etc/apt/sources.list.d/pve-enterprise.list
  - /etc/apt/sources.list.d/pvetest-for-beta.list

Modernizing will replace .list files with the new .sources format,
add Signed-By values where they can be determined automatically,
and save the old files into .list.bak files.

This command supports the 'signed-by' and 'trusted' options. If you
have specified other options inside [] brackets, please transfer them
manually to the output files; see sources.list(5) for a mapping.

For a simulation, respond N in the following prompt.
Rewrite 3 sources? [Y/n] Y

Modernizing /etc/apt/sources.list...
- Writing /etc/apt/sources.list.d/debian.sources

Modernizing /etc/apt/sources.list.d/pve-enterprise.list...

Modernizing /etc/apt/sources.list.d/pvetest-for-beta.list...

🤦‍♂️Gotcha – apt modernize-sources

Be careful about the command apt modernize-sources, this will add back the enterprise repo, and that will start to give you errors when running apt-get update command.

Proxmox apt-get update error 401 Unauthorized

Now run these commands. 

rm /etc/apt/sources.list.d/pve-enterprise.sources
rm /etc/apt/sources.list.d/pve-enterprise.list 2>/dev/null

Now test the apt update command. And it should be as you see below, without errors. 

root@pve2:~# apt update
Hit:1 http://security.debian.org/debian-security trixie-security InRelease
Hit:2 http://deb.debian.org/debian trixie InRelease                                                                                        
Hit:3 http://deb.debian.org/debian trixie-updates InRelease                                                                                
Hit:4 https://deb.nodesource.com/node_22.x nodistro InRelease                                                                  
Hit:5 http://download.proxmox.com/debian/pve trixie InRelease                                            
All packages are up to date.

🧠 Final Thought

You just need to follow the steps, be vigilant and it will be alright. If your upgrade depends on luck instead of control, then you’re doing it wrong 😊.

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