WEBrick fails to start default rails app: “uninitialized constant ActiveRecord::ConnectionAdapters::Column::Format”
问题 I'm trying to begin Ruby on Rails development on a Windows machine, but I can't get WEBrick to start the default Rails app. Here's the output from my attempt to create and start the app: C:\Users\my_user>ruby -v ruby 2.2.4p230 (2015-12-16 revision 53155) [i386-mingw32] C:\Users\my_user\Desktop\wkspc>rails new sample_app [...] Bundle complete! 11 Gemfile dependencies, 57 gems now installed. Use `bundle show [gemname]` to see where a bundled gem is installed. C:\Users\my_user\Desktop\wkspc>cd