Prerequisites & Preparation

Complete every item on this page before starting the upgrade on any host. Skipping these checks is the most common cause of a failed upgrade.

NETLAB+ readiness

Warning

Schedule a maintenance window. Do not upgrade while a class or lab reservation is active. Pods should be powered off and there should be no active reservations on the system being serviced.

  • Confirm there are no active or imminent reservations.

  • Take a current backup of your NETLAB+ VM (see Backup NETLAB+ or Backup).

  • Back up any persistent, master, or template pod VMs that you cannot easily rebuild.

Proxmox host readiness

Open a shell on the Proxmox host. In the web UI, navigate to Datacenter > your_server and select Shell (or connect via console/SSH).

Confirm the current version is 8.4.1 or newer:

pveversion

Note

All nodes must be on Proxmox VE 8.4.1+ before upgrading. If you are on an earlier 8.x release, fully update Proxmox VE 8 first with apt update && apt dist-upgrade, then re-check pveversion.

Warning

Use console or IPMI/xClarity access where possible, not just SSH — the network stack and SSH may be interrupted during the upgrade. Ensure at least 5 GB free (ideally 10 GB+) on the root filesystem; check with df -h /.

Run the pve8to9 checklist

Proxmox provides a read-only checklist tool that reports problems to fix before (and after) the upgrade. It makes no changes to your system.

Run the full check and resolve any reported failures or warnings:

pve8to9 --full

Tip

Re-run pve8to9 after fixing each issue, and again after the upgrade, until it reports no remaining problems.

Clusters: upgrade one node at a time

Warning

In a cluster, upgrade one node at a time. A cluster can run a mix of 8.4 and 9 nodes during the transition, but avoid configuration changes until all nodes are on the same version.

  • Migrate or power off the VMs on the node you are about to upgrade.

  • Upgrade and reboot that node fully, verify it, then move to the next node.

  • NDG recommends upgrading the management server first, followed by each host server.

Ceph

Note

The recommended NETLAB+ design uses direct-attached SSD storage on each host and does not use Ceph, so this step usually does not apply. If you have specifically deployed Ceph, you must upgrade it to the Squid (19.2) release before upgrading Proxmox VE. See the official upgrade guide for the Ceph procedure.