You will have to set paths as indicated in the messages.

Pay attention to the messages displayed during installation.

If you run brew install ruby, then it installs and eventually this will cause tainted object compatibility errors with jekyll theme.

Now, run brew install or the version you prefer.

Once this is done, check again brew doctor and verify that it returns Your system is ready to brew.

Install Homebrew) Read the tutorials thoroughly as it requires update in.

Please follow the steps as described (1.

In my case, I uninstalled homebrew completey using this LINK and reinstalled using this LINK. If any warnings are shown, first try to resolve them.

It should return Your system is ready to brew.

If it’s system’s ruby (/usr/bin/…), then you can simply install a local ruby with your choice of version.

These are the links which I went through during my search:

On trying the suggested solutions, I eventually got a message about not having the right permissions.

However, this spiralled to other errors related to unf_ext, commonmarker and other packages suggesting gem pristine installs. The error message suggested to execute bundle install. I use jekyll for my website and few days back when I tried to update my website blog and executed bundle exec jekyll serve, I faced this issue. Here, I’m posting my solution for ruby / jekyll issue after MacOS update.

Gem install jekyll bundler