# Error when starting rails server \[on rails 3\]

**URL:** <https://www.ruby-forum.com/t/error-when-starting-rails-server-on-rails-3/183272>\
**Category:** Rails\
**Created:** [February 11, 2010, 1:56am UTC](https://www.ruby-forum.com/t/error-when-starting-rails-server-on-rails-3/183272 "2010-02-11T01:56:06Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jump28](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d07c76/32.png) [@jump28](https://www.ruby-forum.com/u/jump28)\
**Post date:** [February 11, 2010, 1:56am UTC](https://www.ruby-forum.com/t/error-when-starting-rails-server-on-rails-3/183272/1 "2010-02-11T01:56:06Z")

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Hi all,

I receive an error when starting the server, namely:

~/Documents/blog$ rails server  
/usr/local/lib/site\_ruby/1.8/rubygems.rb:827:in `report_activate_error': RubyGem version error: rack-mount(0.5.0 not ~> 0.4.0) (Gem::LoadError) from /usr/local/lib/site_ruby/1.8/rubygems.rb:261:in`activate’  
from /usr/local/lib/site\_ruby/1.8/rubygems.rb:296:in `activate' from /usr/local/lib/site_ruby/1.8/rubygems.rb:295:in`each’  
from /usr/local/lib/site\_ruby/1.8/rubygems.rb:295:in `activate' from /usr/local/lib/site_ruby/1.8/rubygems.rb:296:in`activate’  
from /usr/local/lib/site\_ruby/1.8/rubygems.rb:295:in `each' from /usr/local/lib/site_ruby/1.8/rubygems.rb:295:in`activate’  
from /usr/local/lib/site\_ruby/1.8/rubygems.rb:68:in `gem’  
from /usr/bin/rails:18

Some background.

- I run Ubuntu Linux (via Windows Virtual PC)

- I did a clean install of rails3. Though I ran into trouble with  
sqlite3-ruby. It turned out I did not install ruby1.8-dev. However in  
sorting this out I added other gems as well. I guess a gem is not  
confured correctly. So I ran gem clean. The error remains though. My  
list of gems is:

- \*\*\* LOCAL GEMS \*\*\*

abstract (1.0.0)  
actionmailer (3.0.0.beta)  
actionpack (3.0.0.beta)  
activemodel (3.0.0.beta)  
activerecord (3.0.0.beta)  
activeresource (3.0.0.beta)  
activesupport (3.0.0.beta)  
arel (0.2.1)  
builder (2.1.2)  
bundler (0.9.3)  
erubis (2.6.5)  
i18n (0.3.3)  
mail (2.1.2)  
memcache-client (1.7.8)  
mime-types (1.16)  
rack (1.1.0)  
rack-mount (0.5.0)  
rack-test (0.5.3)  
rails (3.0.0.beta)  
railties (3.0.0.beta)  
rake (0.8.7)  
sqlite3-ruby (1.2.5)  
text-format (1.0.0)  
text-hyphen (1.0.0)  
thor (0.13.0)  
tzinfo (0.3.16)

ANY HELP is much appreciated.  
Thanks.

J.

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<div class="post-metadata">

**Author:** ![jump28](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d07c76/32.png) [@jump28](https://www.ruby-forum.com/u/jump28)\
**Post date:** [February 11, 2010, 2:03am UTC](https://www.ruby-forum.com/t/error-when-starting-rails-server-on-rails-3/183272/2 "2010-02-11T02:03:01Z")

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On Wed, Feb 10, 2010 at 6:56 PM, Joep A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> RubyGem version error: rack-mount(0.5.0 not ~\> 0.4.0) (Gem::LoadError)

gem install rack-mount -v=0.4.0

–  
Greg D.  
[destiney.com](http://destiney.com) | [gregdonald.com](http://gregdonald.com)

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<div class="post-metadata">

**Author:** ![jump28](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/d07c76/32.png) [@jump28](https://www.ruby-forum.com/u/jump28)\
**Post date:** [February 11, 2010, 12:24pm UTC](https://www.ruby-forum.com/t/error-when-starting-rails-server-on-rails-3/183272/3 "2010-02-11T12:24:54Z")

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Great; this worked like a charm. Thanks.

Funny how the rails 3 beta app works better with an older version of  
this gem.