Rails 3: uninitialized constant IRB::ReadlineInputMethod::Readline (NameError) in Heroku

Question

Ever since we updated to Rails 3.2.13 we've been unable to start the heroku rails console. The server is working just fine, but when we try to run the console, it gives the following error:

Loading production environment (Rails 3.2.13)
/app/vendor/bundle/ruby/1.9.1/gems/aws-s3-0.6.3/lib/aws/s3/extensions.rb:212:in `const_missing_from_s3_library': uninitialized constant IRB::ReadlineInputMethod::Readline (NameError)
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/input-method.rb:113:in `gets'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `call'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `buf_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:286:in `token'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:262:in `lex'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:233:in `block (2 levels) in each_top_level_statement'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:70:in `block in start'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:69:in `catch'
    from /app/vendor/ruby-1.9.3/lib/ruby/1.9.1/irb.rb:69:in `start'
    from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
    from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
    from /app/vendor/bundle/ruby/1.9.1/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

What is going on? Thanks!

Answer 1

Just experienced this myself. As it turns out the rb-readline gem bumped a version that causes rails console, and other things to fail. Try locking it to '~> 0.4.2'.

gem 'rb-readline', '~> 0.4.2'