diff --git a/README.md b/README.md
index 9010bc9..b375a0d 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@
     * [Installation](#install-nginx-ingress)
 * [Cert-Manager (references ingress controller)](#cert-manager)
   * [Installation](#cert-manager-install)
+  * [Cluster-internal CA issuer](#cert-manager-cluster-ca-issuer)
   * [Let´s Encrypt issuer](#cert-manager-le-issuer)
   * [Deploying a LE-certificate with ingress](#cert-manager-ingress)
   * [Deploying a LE-certificate by CRD](#cert-manager-crd)
@@ -39,6 +40,9 @@
   * [Node maintenance](#node-maintenance)
   * [What happens if a node goes down?](#what-happens-node-down)
   * [Dealing with disruptions](#disruptions)
+* [Troubleshooting](#troubleshooting)
+  * [Deleting a stuck namespace](#ts-delete-stuck-namespace)
+  * [Deleting stuck CRDs](#ts-delete-stuck-crd)
 
 # kubectl - BASH autocompletion <a name="user-content-kubectl-bash-autocompletion"></a>
 For current shell only:
@@ -318,6 +322,9 @@ kubectl create namespace cert-manager
 helm install cert-manager --namespace cert-manager --set 'extraArgs={--dns01-recursive-nameservers-only,--dns01-recursive-nameservers=8.8.8.8:53\,1.1.1.1:53}' jetstack/cert-manager
 kubectl -n cert-manager get all
 ```
+## Cluster-internal CA Issuer <a name="user-content-cert-manager-cluster-ca-issuer"></a>
+Docs: https://cert-manager.io/docs/configuration/ca/
+
 ## Let´s Encrypt issuer <a name="user-content-cert-manager-le-issuer"></a>
 Docs: https://cert-manager.io/docs/tutorials/acme/ingress/#step-6-configure-let-s-encrypt-issuer
 ```
@@ -933,3 +940,13 @@ node/k3s-node2 uncordoned
 * https://kubernetes.io/docs/concepts/workloads/pods/disruptions/
 * https://kubernetes.io/docs/tasks/administer-cluster/safely-drain-node/
 
+# Troubleshooting <a name="user-content-troubleshooting"></a>
+## Deleting a stuck namespace <a name="user-content-ts-delete-stuck-namespace"></a>
+```
+kubectl get namespace "stucked-namespace" -o json \
+  | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" \
+  | kubectl replace --raw /api/v1/namespaces/stucked-namespace/finalize -f -
+```
+
+## Deleting stuck CRDs <a name="user-content-ts-delete-stuck-crd"></a>
+https://github.com/kubernetes/kubernetes/issues/60538#issuecomment-369099998
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