Ubuntu desktop on Proxmox

What you'll build

Before you start

You need Proxmox VE 9.2 already running and reachable on your network. Installing Proxmox isn't covered here.

Firmware settings

Set these in the host's BIOS or UEFI setup. Names vary by board.

Proxmox has supported Secure Boot since version 8.1, so older advice to disable it no longer applies. Some boards reject the boot loader that the 9.2 upgrade installs and stop with a security violation at boot. Only in that case, disable Secure Boot.

Use a wired connection

Proxmox puts VMs on your network through a bridge (vmbr0) on a physical network port. Wi-Fi cards won't carry traffic for other devices, so they can't back a bridge. Connect the host to your router or switch with a cable.

1. Download the Ubuntu ISO

Proxmox can download the installer straight to its own storage, so you don't have to download 6 GB to your laptop and upload it again.

1. In the left-hand tree, select local (pve) > ISO Images > Download from URL.

2. Paste the ISO's address. It must name the .iso file itself; a folder address resolves to a web page, not an image.

   https://releases.ubuntu.com/26.04/ubuntu-26.04-desktop-amd64.iso

3. Click Query URL. Until you do, File name is outlined in red and Download stays grey. Nothing is wrong; Proxmox just won't download a file it hasn't checked.

   

   

4. Click Download and wait for the task log to end in TASK OK. If it ends any other way, the ISO isn't usable; don't continue.

   

The ISO is listed under local (pve) > ISO Images.

2. Create the VM

Click Create VM at the top right. On the General tab, enter a name (the VM ID is filled in), then click Next. Set the remaining tabs as follows.

Choose the installer ISO (OS)

Set the agent and firmware (System)

Size the disk (Disks)

Why SCSI rather than VirtIO Block, SATA or IDE

• SCSI (the default) uses virtio-scsi, where guest and host cooperate instead of the host imitating real hardware. It supports discard and many disks per controller.
• VirtIO Block is just as fast and also supports discard. SCSI wins on consistent /dev/sd* names, more disks per controller and device pass-through.
• SATA and IDE imitate old hardware register by register, which is slow. They exist for systems too old to have VirtIO drivers.

Set the cores and CPU type (CPU)

Set Sockets to 1 and Cores to 4. The VM gets sockets × cores, shown as Total cores. Each virtual core uses one host thread, so a 10-core, 20-thread CPU offers 20. Use 6–8 cores for compiling or rendering, and leave a few threads free for the host.

Set Type to host

Change Type from the default x86-64-v2-AES to host. The default hides CPU features such as AES-NI and AVX2 so VMs can move between different machines. On a single host there's nowhere to move to, so host makes encryption, compression and number-crunching faster at no cost.

Set memory and keep network defaults (Memory, Network)

Set Memory to 8192 MiB. Ubuntu Desktop runs in 4096 but swaps once a browser is open. Leave the host several gigabytes for itself; Proxmox won't stop you giving it all away.

On the Network tab, keep the defaults:

Review and finish (Confirm)

Check the summary against the table below; this is the last easy moment to fix a mistake. Leave Advanced unchecked and click Finish.

What each line means

3. Fix the update error

A fresh Proxmox install uses the enterprise package repositories, which refuse access without a paid subscription. Updating the package list fails with exit code 100:

Open pve > Updates > Repositories. Two rows point at enterprise.proxmox.com:

1. Select pve-enterprise.sources and click Disable.
2. Select pve-ceph.sources and click Disable.
3. Click Add, choose No-Subscription and confirm.
4. Click Reload, then update the package list again.

From the shell instead: Proxmox 9 keeps repositories in /etc/apt/sources.list.d/*.sources as multi-line entries. To disable one, add Enabled: false to its file:

cat /etc/apt/sources.list.d/*.sources
echo 'Enabled: false' | sudo tee -a /etc/apt/sources.list.d/pve-ceph.sources
sudo apt update

The update finishes without error. A banner saying the no-subscription repository “is not recommended for production use” remains; that's expected for a home or lab host.

4. Start the VM

A new VM is stopped, so Console shows VM 100 not running (500). The console only exists while the VM runs.

1. Click OK to close the error.
2. Click Start in the top bar and wait for the VM's icon in the left tree to turn green.
3. Click Console.

The Ubuntu logo appears in the console. Click inside it to send your keyboard and mouse to the VM.

5. Install Ubuntu

Follow the guided installer. Three screens need a decision.

Proprietary software

• Third-party software for graphics and Wi-Fi: leave unchecked. It's for physical hardware the VM doesn't have.
• Support for additional media formats: check it if you'll play video or audio in the VM.

Account

Choose a local account, not Active Directory, which needs a Windows domain controller. Enter your name, a computer name, a username and a password.

Erase disk

Erase disk and install Ubuntu only affects the VM's 64 GiB virtual disk. The host's drives, Proxmox and other VMs are invisible to the installer.

Remove the installation medium

When asked to remove the installation medium, click inside the console and press Enter. If the VM doesn't start the installed system, detach the ISO under Hardware > CD/DVD Drive and check Options > Boot Order.

6. After the install

With Ubuntu running, install the guest agent and set up remote desktop for daily use.

Install the guest agent

This is the Ubuntu half of the Qemu Agent box on the System tab in step 2.

sudo apt update && sudo apt install -y qemu-guest-agent
sudo systemctl enable --now qemu-guest-agent

The VM's summary in Proxmox shows its IP address and real memory use instead of Guest Agent not running, and Shutdown now shuts Ubuntu down cleanly.

Remote desktop for daily use

Not tested: the captured session ended at the install, and GNOME moves these settings between releases, so the menu path on 26.04 may differ.

The browser console is fine for installing and rescue, but has no shared clipboard or sound. GNOME's built-in remote desktop is better day to day.

1. In Ubuntu, open Settings > System > Remote Desktop.
2. Turn on desktop sharing and remote control.
3. Set the remote desktop username and password. They're separate from your Ubuntu login.
4. From another computer, connect with an RDP client (Windows Remote Desktop, Microsoft Remote Desktop on macOS, or Remmina on Linux) to the IP address shown in Proxmox.

Testing and references

Tested September 2, 2026 on Proxmox VE 9.2.2, with screenshots from that one session on one machine. They don't show:

• installing Proxmox itself, or the firmware settings (every board differs);
• Discard checked, or the Ceph repository disabled (both missed in the session);
• VirtIO-GPU on the System tab, or q35 (the graphics card was changed later; the machine type wasn't);
• the media codecs checked;
• the guest agent or remote desktop steps.

The screenshots are 1024 pixels wide or less, so small interface text is soft; the text and tables give every setting you need.

• Proxmox VE Administration Guide: QEMU/KVM virtual machines
• Proxmox VE: package repositories
• Proxmox VE: host boot loader and Secure Boot
• Ubuntu releases