Helm Client down grade

$ helm list
Error: incompatible versions client[v2.10.0] server[v2.9.1]

Like the OP, I had this error:

$ helm list
Error: incompatible versions client[v2.10.0] server[v2.9.1]

Updating the server wasn’t an option for me so I needed to brew install a previous version of the client. I hadn’t previously installed client[v2.9.1] (or any previous client version) and thus couldn’t just brew switch kubernetes-helm 2.9.1. I ended up having to follow the steps in this SO answer: https://stackoverflow.com/a/17757092/2356383

Which basically says

• Look on Github for the correct kubernetes-helm.rb file for the version you want (2.9.1 in my case): https://github.com/Homebrew/homebrew-core/search?q=kubernetes-helm&type=Commits
• Click the commit hash (78d6425 in my case)
• Click the “View” button to see the whole file
• Click the “Raw” button
• And copy the url: https://raw.githubusercontent.com/Homebrew/homebrew-core/78d64252f30a12b6f4b3ce29686ab5e262eea812/Formula/kubernetes-helm.rb

Now that I had the url for the correct kubernetes-helm.rb file, I ran the following:

$ brew unlink kubernetes-helm
$ brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/78d64252f30a12b6f4b3ce29686ab5e262eea812/Formula/kubernetes-helm.rb
$ brew switch kubernetes-helm 2.9.1

Hope this helps someone