"Error: forwarding ports: Upgrade request required" Error in helm of a kubernetes cluster
See my answer here:

Ran into this today when trying to use Garden.io for a cluster running in Jelastic.
Found the solution in this Github comment:
First acquire a local binary for Tiller (server-version of Helm), either by compiling or by downloading it from the release page.
Then run:
$ export HELM_HOST=&quot;:44134&quot;
$ tiller -listen ${HELM_HOST} -alsologtostderr &gt;/dev/null 2&gt;&amp;1 &amp;

This will run a local version of the Kubernetes Helm Server. Now try your original command again, kubectl, that will delegate to this local Helm instead and manage to connect.