Rails uninitialized constant Rack

Question

I tried to setup a rails 5.0.0 app following this on ubuntu 16.04, when I start rails server for the first time, it crashed with the following message. I am new to ruby and do not know what is wrong

/var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/server.rb:8:in <module:Rails>': uninitialized constant Rack (NameError) Did you mean? Rake from /var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/server.rb:7:in <top (required)>' from /var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:138:in require' from /var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:138:in require_command!' from /var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:83:in server' from /var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/commands_tasks.rb:49:in run_command!' from /var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands.rb:18:in <top (required)>' from bin/rails:4:in require' from bin/rails:4:in <main>'

and here is the first 10 lines of

/var/lib/gems/2.3.0/gems/railties-5.0.0/lib/rails/commands/server.rb

require 'fileutils'
require 'optparse'
require 'action_dispatch'
require 'rails'
require 'rails/dev_caching'

module Rails
  class Server < ::Rack::Server
    class Options
      DEFAULT_PID_PATH = File.expand_path("tmp/pids/server.pid").freeze

score 0 · Answer 1 · answered Jul 29 '16 at 09:19

0

Could you please try these commands on your project path;

bundle update

gem update

answered Jul 29 '16 at 09:19

utkuDAT

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After i tried the commands above(eh..`sudo gem update` instead of `gem update` because some errors), it crashed again with the same message :-( – Fallenwood Jul 30 '16 at 02:45
Just remove all of them with `sudo apt-get purge ruby rubygems` then re-install them. – utkuDAT Jul 30 '16 at 04:40
consider using a ruby version manager instead of using the system ruby for development. Good one are rvm rbenv switch-ruby etc.. – Ivailo Bardarov Dec 12 '20 at 11:58
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**Caution** `gem update` corrupted my `ruby-install`ed 2.7.2 version and I had to reinstall it. See https://stackoverflow.com/a/57177186/960184 – Richard Logwood Jan 16 '21 at 20:02
remove all gems and reinstall ```gem uinistall -aIx``` – Almokhtar Feb 07 '22 at 17:53

Rails uninitialized constant Rack

1 Answers1