I was having the following error when running warbler war on my rails application folder: Cannot load gem at [/home/juanito/jruby-1.1.4/lib/ruby/gems/1.8/cache/activerecord-jdbc-adapter-0.8.2.gem] in /home/juanito/bulletonrails/svn_copy/bullet_gui /home/juanito/jruby-1.1.4/lib/ruby/site_ruby/1.8/rubygems/format.rb:41:in `from_file_by_path' I looked around the gems/1.8/cache folder and sure enough, the gem file for activerecord-jdbc-adapter was missing. I had deleted that file and other gem files from that folder a while ago because I thought I would not need them and they was taking space. Well, it turns out that Warbler uses the gem files from the rubygem's cache folder to unpack the gems into the WEB-INF folder. As a consequence, by basically using the original gem files, it bypasses any modification you make to your local gems. So if your newly deployed jruby WAR application is missing custom behavior that you added to your local gems, you may want to convert the gem...
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