kubernetes/kops · error

error serializing addons: %v

Error message

error serializing addons: %v

What it means

For addons of type 'additionalObjects', Build creates an in-memory manifest location and serializes the objects to YAML via ToYAML(). This error is returned if that serialization fails, blocking generation of the addon source bytes.

Source

Thrown at upup/pkg/fi/cloudup/bootstrapchannelbuilder/bootstrapchannelbuilder.go:180

				applyAdditionalObjectsToCluster = append(applyAdditionalObjectsToCluster, addon)
			}
		}
	}

	if len(applyAdditionalObjectsToCluster) != 0 {
		key := "cluster-addons.kops.k8s.io"
		location := key + "/default.yaml"

		addon := addons.Add(&channelsapi.AddonSpec{
			Name:     new(key),
			Selector: map[string]string{"k8s-addon": key},
			Manifest: new(location),
		})
		addon.SkipRemap = true

		manifestBytes, err := applyAdditionalObjectsToCluster.ToYAML()
		if err != nil {
			return fmt.Errorf("error serializing addons: %v", err)
		}
		addon.Source = fi.NewBytesResource(manifestBytes)
		addon.SkipRender = true
	}

	preRegisterAddonImages := b.shouldPreRegisterAddonImages()

	var addonTasks []*AddonManifest
	for _, addon := range addons.Items {
		if preRegisterAddonImages {
			if err := addon.CollectImages(b.assetBuilder, b.addonRenderer); err != nil {
				klog.Warningf("unable to pre-register addon images for %q: %v", addonKey(addon.Spec), err)
			}
		}

		task := &AddonManifest{
			Name:      new(b.Cluster.ObjectMeta.Name + "-addons-" + addonKey(addon.Spec)),
			Lifecycle: b.Lifecycle,

View on GitHub (pinned to 4c8573c808)

Solutions

1. Inspect the wrapped %v error to find the failing object/field
2. Fix or regenerate the additionalObjects in the addon channel manifest
3. Remove the addon entry if the objects are no longer needed
4. Upgrade kops/addon channel to compatible versions

Example fix

// before (channel yaml)
additionalObjects:
- apiVersion: v1
  kind: ConfigMap
  unknownField: <custom type>
// after: only standard serializable objects
additionalObjects:
- apiVersion: v1
  kind: ConfigMap
  metadata:
    name: my-config

// Validate additionalObjects decode as Kubernetes objects first
for _, obj := range addon.Spec.AdditionalObjects {
    if obj.APIVersion == "" || obj.Kind == "" {
        return fmt.Errorf("additionalObject %v missing apiVersion/kind", obj)
    }
}

yamlBytes, err := applyAdditionalObjectsToCluster.ToYAML()
if err != nil {
    return fmt.Errorf("cannot serialize additionalObjects addon: %w", err)
}

When it happens

Trigger: Building a cluster whose spec.addons include an addon with additionalObjects (or additionalObjects addons provided externally) where one of the embedded Kubernetes objects cannot be converted to YAML by applyAdditionalObjectsToCluster.ToYAML().

Common situations: additionalObjects entries with fields that fail YAML/JSON marshaling (e.g. raw nested values from a hand-written channel); version skew between kops and the addon channel format.

Related errors

• error serializing addons yaml: %v
• unable to marshal YAML: %v
• error converting to yaml: %v
• marshaling to yaml for %v: %w
• error marshaling manifest to yaml: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/577dfac067baa774. Report an issue: GitHub.