TechnitiumSoftware/DnsServer · error · DnsServerException

Failed to ask Secondary node to leave: only a Primary node c

Error message

Failed to ask Secondary node to leave: only a Primary node can ask a Secondary node to leave the Cluster.

What it means

Thrown by AskSecondaryNodeToLeaveClusterAsync when the current server's self node is not the Primary node. Only the Primary can instruct a Secondary to gracefully leave, because the leave handshake involves the Primary updating its node list, zone records, and catalog zone.

Source

Thrown at DnsServerCore/Cluster/ClusterManager.cs:749

            //save all changes
            SaveConfigFile();

            //notify all secondary nodes
            TriggerNotifyAllSecondaryNodes();

            //trigger NS and SOA update for member zones
            TriggerRecordUpdateForClusterCatalogMemberZones();

            return secondaryNode;
        }

        public async Task<ClusterNode> AskSecondaryNodeToLeaveClusterAsync(int secondaryNodeId)
        {
            if (!ClusterInitialized)
                throw new DnsServerException("Failed to ask Secondary node to leave: the Cluster is not initialized.");

            if (GetSelfNode().Type != ClusterNodeType.Primary)
                throw new DnsServerException("Failed to ask Secondary node to leave: only a Primary node can ask a Secondary node to leave the Cluster.");

            //find existing secondary node
            if (!_clusterNodes.TryGetValue(secondaryNodeId, out ClusterNode secondaryNode))
                throw new DnsServerException("Failed to ask Secondary node to leave: the specified node does not exist in the Cluster.");

            if (secondaryNode.Type == ClusterNodeType.Primary)
                throw new DnsServerException("Failed to ask Secondary node to leave: the specified node is the Cluster Primary node and cannot be removed.");

            //ask secondary node to leave the cluster
            await secondaryNode.AskSecondaryNodeToLeaveClusterAsync();

            return secondaryNode;
        }

        public ClusterNode DeleteSecondaryNode(int secondaryNodeId)
        {
            if (!ClusterInitialized)
                throw new DnsServerException("Failed to delete Secondary node: the Cluster is not initialized.");

View on GitHub (pinned to d0484b6c1e)

Solutions

Run AskSecondaryNodeToLeaveClusterAsync on the cluster Primary node.
Verify GetSelfNode().Type == ClusterNodeType.Primary before calling.

Example fix

// before
await _clusterManager.AskSecondaryNodeToLeaveClusterAsync(nodeId);
// after
if (_clusterManager.GetSelfNode().Type != ClusterNodeType.Primary)
    throw new InvalidOperationException("Run on the Primary node.");
await _clusterManager.AskSecondaryNodeToLeaveClusterAsync(nodeId);

Defensive patterns

Strategy: validation

Validate before calling

if (_dnsWebService.ClusterManager.GetSelfNode().Type != ClusterNodeType.Primary)
    throw new InvalidOperationException("AskSecondaryNodeToLeaveClusterAsync must run on the Primary node.");
await _dnsWebService.ClusterManager.AskSecondaryNodeToLeaveClusterAsync(nodeId);

Type guard

static bool IsPrimaryNode(ClusterManager cm)
    => cm.ClusterInitialized && cm.GetSelfNode().Type == ClusterNodeType.Primary;

Try / catch

try
{
    await _clusterManager.AskSecondaryNodeToLeaveClusterAsync(nodeId);
}
catch (DnsServerException ex) when (ex.Message.Contains("only a Primary node can ask"))
{
    throw new InvalidOperationException("Redirect this request to the cluster Primary node.", ex);
}

Prevention

Route all leave requests to the Primary node.
Check GetSelfNode().Type before calling node-removal methods.
Pin cluster-management endpoints to the Primary in load-balanced setups.

When it happens

Trigger: AskSecondaryNodeToLeaveClusterAsync is called from a Secondary node. The guard at line 748 fires after the ClusterInitialized check.

Common situations: The leave API request is sent to a Secondary instead of the Primary; wrong server targeted in a multi-node setup.

Related errors

AI-assisted analysis of TechnitiumSoftware/DnsServer@d0484b6c1e (2026-08-13). Data as JSON: /api/errors/124ddb44fa4bb799. Report an issue: GitHub.