How to fix a bundle install “nio4r error” on Rails 5.0.0

Question

The exact error is:

An error occurred while installing nio4r (1.2.1), and bundler cannot continue. Make sure that \'gem install nio4r -v \'1.2.1\'\' succeeds         


        

Answer 1

If anyone is looking for this, I had updated my computer and the command line tools were updated. I needed to agree to the XCode license.

Error: You have not agreed to the Xcode license. Please resolve this
 by running:   sudo xcodebuild -license accept

This fixed it for me.