Installing Zammad for Kubernetes with helm gives "Error: create: failed to create: namespaces "zammad" not found"

[sigma]

I am running Ubuntu 20.4 and I have done the following:

1. Install Docker from Install Docker Engine on Ubuntu | Docker Documentation
2. Install Docker Compose with sudo apt install docker-compose
3. Install Kubernetes with sudo apt-get install -y kubelet kubeadm kubectl
4. Add Kubernetes Cluster from Creating a cluster with kubeadm | Kubernetes
5. Install helm

I now try to install Zammad but I get error “Error: create: failed to create: namespaces “zammad” not found”:

m@oter:~$ helm repo add zammad https://zammad.github.io/zammad-helm
"zammad" has been added to your repositories
m@oter:~$ helm upgrade --install zammad zammad/zammad --namespace=zammad
Release "zammad" does not exist. Installing it now.
Error: create: failed to create: namespaces "zammad" not found

Infos:

• Used Zammad version: 5.21
• Used Zammad installation type: Install on Kubernetes via Helm — Zammad documentation
• Operating system: Ubuntu 20.4
• Browser + version: Firefox latest

Expected behavior:

• Install OK

Actual behavior:

• Error: create: failed to create: namespaces “zammad” not found

Steps to reproduce the behavior:

• helm repo add zammad Zammad Helm chart | zammad-helm

• helm upgrade --install zammad zammad/zammad --namespace=zammad