Kubernetes Helm Error: UPGRADE FAILED: another operation (install/upgrade/rollback) is in progress.

The error

When trying a helm command on my AKS cluster recently I received the following error:

Error: UPGRADE FAILED: another operation (install/upgrade/rollback) is in progress

The command I was attempting was to update my version of kube-prometheus-stack to version 30.0.0, but you may see this when running any helm install, upgrade or rollback operations.

helm upgrade prometheus-operator prometheus-community/kube-prometheus-stack --install --namespace prometheus --wait --timeout 36000s --version=30.0.0 --set grafana.adminPassword=testpass

You may also note that when running the command:

helm ls --namespace <namespace>

In my case:

helm ls --namespace prometheus

Shows the following with no information:

The fix!

To debug this, I checked the history of the previous deployment:

helm history <release> --namespace <namespace>

In my case:

helm history prometheus-operator --namespace prometheus