运行后gem update
,当我尝试启动 rails 时出现以下错误:
$ rails s
/usr/lib/ruby/1.9.1/rubygems.rb:238:in `activate': can't activate rack (~> 1.4.5, runtime)
for ["actionpack-3.2.12", "railties-3.2.12"], already activated rack-1.5.2 for ["rack-
ssl-1.3.3", "railties-3.2.12"] (Gem::LoadError)
from /usr/lib/ruby/1.9.1/rubygems.rb:254:in `block in activate'
from /usr/lib/ruby/1.9.1/rubygems.rb:253:in `each'
from /usr/lib/ruby/1.9.1/rubygems.rb:253:in `activate'
from /usr/lib/ruby/1.9.1/rubygems.rb:254:in `block in activate'
from /usr/lib/ruby/1.9.1/rubygems.rb:253:in `each'
from /usr/lib/ruby/1.9.1/rubygems.rb:253:in `activate'
from /usr/lib/ruby/1.9.1/rubygems.rb:1065:in `gem'
from /usr/local/bin/rails:18:in `<main>'
谁能帮助我,这意味着什么以及如何解决问题?