[Helm] ArgoCD-provided .Capabilities.KubeVersion.Version is inconsistent with Helm

[fuljo]

Checklist:

• I've searched in the docs and FAQ for my answer: https://bit.ly/argocd-faq.
• I've included steps to reproduce the bug.
• I've pasted the output of argocd version.

Describe the bug

If you deploy an Helm Application that uses .Capabilities.KubeVersion.Version in its chart's template, the result is inconsistent if the user does not explicitly specify helm.kubeVersion.

• Helm (tested with v3.19.5) outputs a format like v1.34.0.
• ArgoCD (tested with v3.3.0) outputs a format like v1.34.

This is making the installation of kube-prometheus-stack fail because it relies on the full semver to pull the kubectl image (see https://github.com/prometheus-community/helm-charts/blob/a3300192e5ff039d59db6209811f21fda9033b80/charts/kube-prometheus-stack/charts/crds/templates/upgrade/job.yaml#L78).

Other charts that rely on reading the full value (major.minor.patch) may fail too.

To Reproduce

1. Produce a minimal chart with this template:

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: debug-cm
   data:
     direct: "{{ .Capabilities.KubeVersion.Version }}"

2. Render it with Helm

   helm template debug-chart ./debug-chart --debug

3. Deploy an ArgoCD application that uses the chart

   apiVersion: argoproj.io/v1alpha1
   kind: Application
   metadata:
     name: debug-app
     namespace: argocd
   spec:
     destination:
       server: https://kubernetes.default.svc
       namespace: default
     project: default
   
     sources:
       - repoURL: https://github.com/example/example.git
         path: debug-chart
         targetRevision: "main"
   

Expected behavior

Helm and ArgoCD shall have the same behavior.

Version

argocd: v3.2.3+unknown
  BuildDate: 2025-12-29T04:22:33Z
  GitCommit:
  GitTreeState:
  GitTag: 3.2.3
  GoVersion: go1.25.5 X:nodwarf5
  Compiler: gc
  Platform: linux/amd64
argocd-server: v3.3.0
  BuildDate: 2026-02-02T07:28:36Z
  GitCommit: fd6b7d5b3cba5e7aa7ad400b0fb905a81018a77b
  GitTreeState: clean
  GitTag: v3.3.0
  GoVersion: go1.25.5
  Compiler: gc
  Platform: linux/amd64
  Kustomize Version: v5.8.0 2025-11-09T14:39:49Z
  Helm Version: v3.19.4+g7cfb6e4
  Kubectl Version: v0.34.0
  Jsonnet Version: v0.21.0

Possible cause
This might happen because the value that ArgoCD passes to helm template --kube-version <value> is gotten from this cached entry, which explicitly prints just <major>.<minor>:

argo-cd/util/db/cluster.go

Lines 38 to 55 in 76162a9

	func (db *db) getLocalCluster() *appv1.Cluster {
	initLocalCluster.Do(func() {
	info, err := db.kubeclientset.Discovery().ServerVersion()
	if err == nil {
	localCluster.Info.ServerVersion = fmt.Sprintf("%s.%s", info.Major, info.Minor)
	localCluster.Info.ConnectionState = appv1.ConnectionState{Status: appv1.ConnectionStatusSuccessful}
	} else {
	localCluster.Info.ConnectionState = appv1.ConnectionState{
	Status: appv1.ConnectionStatusFailed,
	Message: err.Error(),
	}
	}
	})
	cluster := localCluster.DeepCopy()
	now := metav1.Now()
	cluster.Info.ConnectionState.ModifiedAt = &now
	return cluster
	}

NOTE: I've tried to track the source value down, but I'm not very familiar with the code.

[ppapapetrou76]

@fuljo thank for reporting this
ArgoCD 3.3 ships with helm 3.19.4 but I can't see any related changes introduced in helm 3.19.5 so probably it's something that is not affected by helm binary

I'll have a look at the code you pointed out and get back to. you

[thomas-bright]

I've also encountered this problem today: upgraded last week ArgoCD to v3.3.0 and tried to sync a Chart using kube-prometheus-stack Helm Chart, which is failing now.

The relevant change in Helm happened with Helm's PR #31091, which was released in v3.19.0.
Before this change, library github.com/Masterminds/semver/v3 was used, which handled parsing of version strings differently than the change now does.

From semver's README:

The NewVersion function attempts to coerce a version into a semantic version and parse it. For example, if there is a leading v or a version listed without all 3 parts (e.g. v1.2) it will attempt to coerce it into a valid semantic version (e.g., 1.2.0).

And in the current version, that 'auto-completion' to a 3-part semver version is no longer present.

The combination of ArgoCD stripping the patch version in its initial version retrieval in gitops-engine/pkg/utils/kube/ctl.go's GetServerVersion(), with the new behaviour of Helm 3.19.x not autocompleting to a 3-part semver, makes the kube-prometheus-stack Chart crd upgrade job fail.

If ArgoCD were to use the full semver version as the default kubeVersion for Helm templating, this problem would be solved.

Impact of this issue: any Helm chart that uses .Capabilities.KubeVersion.Version and expectsa complete semantic version (major.minor.patch).

[ppapapetrou76]

I confirmed the issue on the latest version of ArgoCD and I'm going to provide a fix + Unit tests