exec plugin: invalid apiVersion "client.authentication.k8s.io/v1alpha1"

Your kubeconfig exec plugin entry still uses the v1alpha1 client authentication API, which kubectl removed in v1.26. Bump the apiVersion in that user block to client.authentication.k8s.io/v1beta1 (or v1) - and upgrade the auth plugin binary (aws-iam-authenticator, kubelogin, etc) if it is old. kubectl works again on the next command.

The error

error: exec plugin: invalid apiVersion "client.authentication.k8s.io/v1alpha1"

What to do

1. Find the offending entry:

grep -n "client.authentication.k8s.io/v1alpha1" ~/.kube/config

Expected: Shows the user block using the old apiVersion.

1. Edit that user block so the exec stanza reads:

users:
- name: [your-user]
  user:
    exec:
      apiVersion: client.authentication.k8s.io/v1beta1
      command: [your-auth-plugin]

Expected: File saves cleanly.

1. If the plugin binary is old, upgrade it too - e.g. aws-iam-authenticator version

Expected: Prints a recent version, no error.

1. Verify:

kubectl cluster-info

Expected: Prints cluster info instead of the exec plugin error.

When this applies

• kubectl 1.26 or newer
• kubeconfig users with an exec stanza (EKS, kubelogin, gardener, custom OIDC plugins)
• the exact invalid apiVersion v1alpha1 message

When it does NOT apply

• exec errors mentioning v1beta1 or v1
• static bearer tokens or client certs in kubeconfig
• plugin binary missing from PATH (different error)

Works with

kubectl v1.26+; aws-iam-authenticator, kubelogin, gke-gcloud-auth-plugin recent releases

exec plugin: invalid apiVersion "client.authentication.k8s.io/v1beta1"

Same failure one API version newer. Same fix: move the exec apiVersion to v1.

Why it happens

Kubernetes deprecated the v1alpha1 exec credential API and kubectl 1.26 stopped parsing it entirely. Old kubeconfig generators (and old plugin docs) still emit v1alpha1, so the config and the client disagree.

Edge cases

• Managed kubeconfig generators (aws eks update-kubeconfig, gcloud get-credentials) can rewrite the file and reintroduce the old apiVersion - re-check after regenerating.
• Some very old plugins only speak v1alpha1: then the real fix is upgrading the plugin, not editing the version string.

Resolved from

gh:harishgorla5/project04#1 - https://github.com/harishgorla5/project04/issues/1