在配置gem的过程中，有极小机率会遇到gem安装后失效的问题，比方说会403，如下所示：
C:\Users\geraldlau>gem update --system
Updating RubyGems...
ERROR: While executing gem ... (Gem::RemoteSourceException)
HTTP Response 403
C:\Users\geraldlau>gem install rubygems-update
ERROR: While executing gem ... (Gem::RemoteSourceException)
HTTP Response 403
C:\Users\geraldlau>gem sources -r http://gems.rubyforge.org
ERROR: While executing gem ... (Gem::RemoteSourceException)
HTTP Response 403
这是一个很神奇的事情，所以说这个世界充满了奇妙。遇到这个问题，本地是无论如何都没法使用gem的了，只有去官方重新下载最新版的gem，本地安装后才能修复。
直接到http://rubyforge.org/frs/?group_id=126，下载最新版本的gem，然后本地安装。如果是win环境，建议拉zip包，若在linux下面，就随便拉哪种都行了。把gem包拉到本地并解压后，安装它：
C:\>cd rubygems-1.3.5
C:\rubygems-1.3.5>dir/w
驱动器 C 中的卷是 WIN7
卷的序列号是 5E56-471B
C:\rubygems-1.3.5 的目录
[.] [..] .autotest .docume
[bin] ChangeLog cruise_config.rb GPL.txt
History.txt [lib] LICENSE.txt Manifes
[pkgs] Rakefile README setup.r
[test] [util]
11 个文件 270,420 字节
7 个目录 14,917,832,704 可用字节
C:\rubygems-1.3.5>setup.rb
RubyGems 1.3.5 installed
锘?== 1.3.5 / 2009-07-21
Bug fixes:
* Fix use of prerelease gems.
* Gem.bin_path no longer escapes path with spaces. Bug #25935 an
Deprecation Notices:
* Bulk index update is no longer supported (the code currently r
the tests)
* Gem::manage_gems was removed in 1.3.3.
* Time::today was removed in 1.3.3.
----------------------------------------------------------------
RubyGems installed the following executables:
c:/ruby/bin/gem
C:\rubygems-1.3.5>
至此，搞定它了。
来源：oschina
链接：https://my.oschina.net/u/84549/blog/13952