What causes "found VMSS without IP config properties" in kubernetes/kops?

Re-fetch / re-apply after the VMSS update settles and confirm the error clears.

found VMSS without IP config properties

Error message

found VMSS without IP config properties

What it means

Find requires the selected IP configuration's Properties block to be non-nil in order to read the Subnet reference. An IP config without Properties carries no subnet information, so Find cannot map the VMSS to a kops subnet and returns this error.

Source

Thrown at upup/pkg/fi/cloudup/azuretasks/vmscaleset.go:141

	}

	profile := found.Properties.VirtualMachineProfile

	nwConfigs := profile.NetworkProfile.NetworkInterfaceConfigurations
	if len(nwConfigs) != 1 {
		return nil, fmt.Errorf("expecting exactly 1 network interface config for %q, found %d: %+v", *s.Name, len(nwConfigs), nwConfigs)
	}
	nwConfig := nwConfigs[0]
	if nwConfig.Properties == nil {
		return nil, fmt.Errorf("found VMSS without network interface config properties")
	}
	ipConfigs := nwConfig.Properties.IPConfigurations
	if len(ipConfigs) != 1 {
		return nil, fmt.Errorf("expecting exactly 1 network interface IP config for %q, found %d: %+v", *s.Name, len(ipConfigs), ipConfigs)
	}
	ipConfig := ipConfigs[0]
	if ipConfig.Properties == nil {
		return nil, fmt.Errorf("found VMSS without IP config properties")
	}
	if ipConfig.Properties.Subnet == nil {
		return nil, fmt.Errorf("found VMSS without IP config subnet")
	}
	if ipConfig.Properties.Subnet.ID == nil {
		return nil, fmt.Errorf("found VMSS without IP config subnet ID")
	}
	subnetID, err := azure.ParseSubnetID(*ipConfig.Properties.Subnet.ID)
	if err != nil {
		return nil, fmt.Errorf("failed to parse subnet ID %s", *ipConfig.Properties.Subnet.ID)
	}

	var loadBalancerID *azure.LoadBalancerID
	if ipConfig.Properties.LoadBalancerBackendAddressPools != nil {
		for _, i := range ipConfig.Properties.LoadBalancerBackendAddressPools {
			if !strings.Contains(*i.ID, "api") {
				continue
			}

View on GitHub (pinned to 4c8573c808)

Solutions

Re-fetch / re-apply after the VMSS update settles and confirm the error clears.
Set Properties on the mocked VirtualMachineScaleSetIPConfiguration in tests.
Recreate a persistently malformed VMSS via kops apply.

Example fix

// before
ip := &compute.VirtualMachineScaleSetIPConfiguration{Name: &name}
// after
ip := &compute.VirtualMachineScaleSetIPConfiguration{Name: &name, Properties: &compute.VirtualMachineScaleSetIPConfigurationProperties{}}

Defensive patterns

Strategy: validation

Validate before calling

ip := ips[0]
if ip.Properties == nil {
    return fmt.Errorf("IP config %s has no properties; recreate VMSS", fi.ValueOf(ip.Name))
}

Type guard

func hasIPProperties(ip *compute.VirtualMachineScaleSetIPConfiguration) bool {
    return ip != nil && ip.Properties != nil
}

Try / catch

found, err := task.Find(ctx, cloud)
if err != nil {
    if strings.Contains(err.Error(), "without IP config properties") {
        return refetchAfterUpdate(err)
    }
    return err
}

Prevention

Set Properties in every mocked IPConfiguration.
Avoid reconciling while the VMSS is mid-mutation.
Pin the azure-sdk-for-go version used by kops.

When it happens

Trigger: ipConfigs[0].Properties == nil — an IP configuration entry returned with only its name populated, typical of partial responses or incomplete fixtures.

Common situations: Mocked SDK responses missing Properties; Azure API returning a sparse entry mid-mutation; SDK version mismatch changing field population.

Related errors

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/5919bb09005ad6af. Report an issue: GitHub.