Problem:

While trying to update ruby gems:

    gem update

I ran into the following error:

    SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed

I'd recently installed a new certificate so I assumed it was that. However after a lot of hunting around it turns out that there was an SSL certificate update for ruby gems. See here

Solution:

In order to fix this you need to manually update RubyGems:

First download the new package from here to somewhere easy to type on your machine (I downloaded it to root of d in the same fashion as the link above shows)

Now type each of the following lines and you will be good to go:

    gem install --local D:\rubygems-update-2.6.7.gem
    update_rubygems --no-ri --no-rdoc
    gem uninstall rubygems-update -x

Instructions reproduced from here.