What does "cluster not ready – no quorum" mean? This error indicates that your Proxmox VE (PVE) cluster is unable to function properly because it lacks a majority of nodes required to maintain a stable, operational state. In a cluster, quorum refers to the minimum number of nodes that must be online and communicating to make decisions (such as starting or migrating virtual machines). If the cluster loses quorum, it cannot perform critical operations, and virtual machines may be stopped or fail over.

In a typical two-node cluster, both nodes must be online to maintain quorum. If one node fails or disconnects, the remaining node cannot act alone — hence the "no quorum" error. This is a safety mechanism to prevent split-brain scenarios where nodes make conflicting decisions.

Common causes of "no quorum" in Proxmox clusters:

• A node has gone offline due to hardware failure, network issues, or power loss.
• Network connectivity problems between nodes.
• Misconfigured or missing cluster configuration files.
• One or more nodes have been manually removed or are out of sync.
• The cluster has been split due to network partitioning.

How to fix "cluster not ready – no quorum" quickly

If you're certain that only one node should be active (e.g., in a two-node cluster where one is down), you can temporarily adjust the expected number of nodes to allow the remaining node to function. This is a short-term fix and should only be used when you are confident that the cluster is safe to operate with a reduced number of nodes.

Step-by-step fix:

1. Log in to the active node

Access the Proxmox VE web interface or SSH into the node that is still online.

1. Check the current cluster status

Run the following command to verify the cluster state:

   pvecm status

Look for the line: Quorum: 0 or No quorum.

1. Set the expected number of nodes to 1

Use the pvecm expected command to reduce the expected number of nodes to 1:

   pvecm expected 1

This tells the cluster that only one node is expected to be active.

1. Verify the change

Run:

   pvecm status

You should now see:

   Quorum: 1

This indicates the cluster has quorum again and can function.

1. Check cluster health

Ensure all services are running:

   pvecm nodes

Confirm the active node is listed and in the "online" state.

1. Monitor the cluster

Use the Proxmox web interface or run:

   pvecm query

to ensure the cluster remains stable.

Important notes:

  pvecm add 

• This fix is not permanent. It should only be used when a node is down and you are not able to restore it immediately.
• If the failed node is recoverable, do not use pvecm expected 1 unless you are certain the node will not return. Otherwise, you risk data inconsistency.
• To restore a two-node cluster, you must bring the second node back online and ensure it rejoins the cluster properly. Use:

(if the node is still accessible).

  systemctl status corosync
  systemctl status pacemaker

• Always ensure network connectivity between nodes and that corosync and pacemaker services are running:

Best practices to prevent future issues:

  cp /etc/pve/corosync.conf /etc/pve/corosync.conf.backup

• Use a three-node cluster where possible — this allows the cluster to survive the failure of one node.
• Ensure all nodes have redundant network connections (e.g., separate VLANs or bonded interfaces).
• Monitor cluster health using email alerts (configure via Datacenter → Options → Email notification).
• Regularly back up cluster configuration:

When to contact support: If the issue persists after setting pvecm expected 1, or if you cannot bring the cluster back to a healthy state, contact the HelpDesk and provide the output of:

pvecm status
pvecm nodes
corosync-cfgtool -s

This will help diagnose deeper issues such as configuration corruption or network misconfigurations.

⚠️ Warning: Using pvecm expected 1 in a production environment without understanding the implications can lead to data loss or service disruption. Always assess the situation before making changes.