Rails - cannot run app: Unable to load the EventMachine C extension;

Question

When I run an app on Lion OS X, I get this error:

Unable to load the EventMachine C extension; To use the pure-ruby reactor, require \'em/pure_ruby\'
/Users/         


        

Answer 1

You may find various errors while installing gems or trying to find solution to your ruby application installation failing due to ruby-devel was not installed.

I just installed on my Kali linux with

sudo apt-get install ruby-dev

and everything resolved. I was trying to install bettercap.

This answer helped: https://stackoverflow.com/a/4502672/6503117