no such file to load -- ffi_c (LoadError)

Question

This problem is bugging me for a couple of days now... Whenever I'm using the .bring_to_front method

require "rubygems"
require "watir"

browser = Watir::Browser::new
browser.bring_to_front

I get this error:

(...)rubygems/custom_require.rb:36:in `require': no such file to load -- ffi_c (LoadError)

I tried uninstalling and reinstalling ffi/watir/ruby/netbeans without success.

line 36 is in custom_require.rb

def require path
if Gem.unresolved_deps.empty? or Gem.loaded_path? path then
  gem_original_require path
else
  spec = Gem.searcher.find_active path
  unless spec then
    found_specs = Gem.searcher.find_in_unresolved path
    unless found_specs.empty? then
      found_specs = [found_specs.last]
    else
      found_specs = Gem.searcher.find_in_unresolved_tree path
    end
    found_specs.each do |found_spec|
      Gem.activate_spec found_spec
    end
  end
  return gem_original_require path #problem
end

* LOCAL GEMS *

archive-tar-minitar (0.5.2)
builder (3.0.0)
childprocess (0.2.2)
columnize (0.3.4)
commonwatir (2.0.4)
ffi (1.0.10 x86-mingw32)
firewatir (1.9.4, 1.8.1)
hoe (2.12.3, 2.8.0)
json (1.6.1)
json_pure (1.6.1)
linecache19 (0.5.12)
minitest (2.7.0, 2.6.2, 1.6.0)
nokogiri (1.5.0 x86-mingw32)
rake (0.9.2.2, 0.9.2, 0.8.7)
rautomation (0.6.3)
rdiscount (1.6.8)
rdoc (3.11, 2.5.8)
require_all (1.2.0)
ruby-debug-base19 (0.11.25)
ruby-debug-ide (0.4.16, 0.4.9)
ruby_core_source (0.1.5)
rubyzip (0.9.4)
s4t-utils (1.0.4)
selenium-webdriver (2.10.0)
user-choices (1.1.6.1)
watir (2.0.4)
watir-webdriver (0.3.5)
win32-api (1.4.8 x86-mingw32)
win32-process (0.6.5)
windows-api (0.4.0)
windows-pr (1.2.1)
xml-simple (1.1.1, 1.1.0)

Answer 1

I think the missing file relates to the FFI gem. I had issues trying to use FFI v1.0.10 myself (when it went to install, and due to something pertaining to webdriver code) so on my box I have v1.0.9 of that gem installed.

I'd say there's not much to lose by trying to roll that gem back a version. From the command line type

gem uninstall ffi

once it's done then

gem install ffi -v 1.0.9

See if that fixes things for you.

Update the FFI gem has since updated past 1.1.0 and these versions seem to work fine with watir and watir-webdriver, however the gem is not pre-compiled, and has to compile code when it installs. This means if you are running on a PC you will need to install the Ruby development kit for windows, aka 'devkit', you can get it from the downloads page on the rubyinstaller site

download and install devkit first, then open a new command line window and use

gem install ffi

to get the latest version of the FFI gem

if for some reason that does not work for you, you can always use the original instructions above to install the slightly older version of the FFI gem