Gem::Exception: can't activate , already activated x

By: Johnathon Wright on: August 05, 2009

I recently saw this exception: [RAILS_ROUTE] /config/../vendor/rails/railties/lib/rails/gemdependency.rb:101:in `specification':Gem::Exception: can't activate , already activated *gemname*

This exception seemed to be the result of several problems intermingling:

  1. rake gems:install wouldn't work because the config.gem statements were in config/environments/test.rb. Only the gems listed in config/environment.rb are installed in gems:install (though I didn't try to manually set the environment to test...)
  2. I had the wrong version of nokogiri. The configuration specified a certain version, instead of any version greater than a certain version.
  3. I also didn't have the gem listed after the gem with the wrong version. When I modified test.rb so that only the gem with the wrong version was listed, I got a more helpful error: Missing these required gems: gem_name = version You're running:ruby at path rubygems 1.3.3 at path

So, the solution: 1. Once I found the gem requirements in test.rb, I deleted half of them and ran script/console. I kept deleting chunks of the requirements until the error went away. 2. Installed the correct version It seems simple in retrospect... but the error was very confusing.


Just checking that you are human. What would be the result of this code?

a = 3*(4/2); b = 1; a+b