Fix Rubygems error: undefined method `source_index' for Gem:Module

Fix Rubygems binary error: undefined method `activate_bin_path' for Gem:Module (NoMethodError)

So you're getting an error like this:

undefined method `activate_bin_path' for Gem:Module (NoMethodError)

Here is what happened:

You installed a recent version of Rubygems
You installed some gems that install a binary (like `bun...

How to fix "undefined method `name' for Array" error when running bundled commands on Ruby 1.8.7 + Rails 2.3

On recent/fresh installations of Ruby 1.8.7 you may encounter this error why calling any bundled binary (or just bundle exec):

/home/arne/.rvm/gems/ruby-1.8.7-p374@global/gems/rubygems-bundler-1.4.2/lib/rubygems-bundler/noexec.rb:75:in ...

NoMethodError: undefined method `cache' for Gem:Module

I got this error when running Rails 2.3 tests for Rails LTS. More stacktrace:

NoMethodError: undefined method `cache' for Gem:Module
    /vagrant/rails-2-3-lts-repository/railties/lib/rails_generator/lookup.rb:212:in `e...

Fixing "undefined local variable or method `version_requirements' for #<Rails::GemDependency:0x...> (NameError)"

Phillip Koebbe from Ruby on Rails suggested inserting following code between the "bootstrap" and "initialize" sections of enviroment.rb. This hack fixes the problem.

if Gem::VERSION >= "1.3.6"
  module Rails
    class GemDependency

...

How to fix: undefined method `specifications' (caused by RubyGems 1.8)

Sometimes, when running a rake task, RubyGems 1.8.5 raises an error:

rake aborted!
undefined method `specifications' for "/usr/lib/ruby/gems/1.8":String

This has been fixed since May 31 but is still not available as a new RubyGems versio...

Fix error: undefined method `desc' for #<Foo::Rake::Taskx1234>

Fix for mysql2 error "Incorrect MySQL client library version! This gem was compiled for x.x.x but the client library is y.y.y."

This should be fixed in the latest LTS-branches of our mysql2 fork, 0.2.x-lts and 0.3.x-lts.

Use

gem 'mysql2', git: 'https://github.com/makandra/mysql2', branch: '0.2.x-lts' # for Rails 2.x
gem 'mys...

Fix Rubygems warning: Gem.source_index is deprecated, use Specification

After updating Rubygems you see a wall of deprecation warnings like this:

NOTE: Gem::SourceIndex#add_spec is deprecated, use Specification.add_spec. It will be removed on or after 2011-11-01.
Gem::SourceIndex#add_spec called from /usr/loc...

Fix: "undefined method `bytesize' for #<Array>"

I believe that when WEBrick has trouble bringing up your Rails application, the WEBrick component that is supposed to print you a pretty error message has a bug and sometimes fails with this message:

"undefined method `bytesize' for #<Array>"...

Fix Rubygems error: undefined method `source_index' for Gem:Module

See also

Related cards: