# Rack error

**URL:** <https://www.ruby-forum.com/t/rack-error/175714>\
**Category:** Rails\
**Created:** [September 18, 2009, 8:39am UTC](https://www.ruby-forum.com/t/rack-error/175714 "2009-09-18T08:39:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![preethi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/f04885/32.png) [@preethi](https://www.ruby-forum.com/u/preethi)\
**Post date:** [September 18, 2009, 8:39am UTC](https://www.ruby-forum.com/t/rack-error/175714/1 "2009-09-18T08:39:10Z")

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Hi

I’ve just started exploring about rack and created by [config.ru](http://config.ru) file  
under config folder in my application.

when I try to run the “rackup” command, I get an error saying  
Configuration [config.ru](http://config.ru) not found.

## I’ve just written these three lines in my [config.ru](http://config.ru) file

## require ‘rack’ require ‘rack/lobster’ run Rack::Lobster.new

Could anyone also please suggest on any good tutorials which would help  
me completely understand about Rack!

Thanks

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<div class="post-metadata">

**Author:** ![preethi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/f04885/32.png) [@preethi](https://www.ruby-forum.com/u/preethi)\
**Post date:** [September 18, 2009, 9:23am UTC](https://www.ruby-forum.com/t/rack-error/175714/2 "2009-09-18T09:23:51Z")

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I would say

[http://rack.rubyforge.org/doc/SPEC.html](http://rack.rubyforge.org/doc/SPEC.html)  
and  
[http://rack.rubyforge.org/doc/](http://rack.rubyforge.org/doc/)  
will be helpful.

-Gourav

On Sep 18, 11:39 am, Preethi S. \<rails-mailing-l…@andreas-

---

<div class="post-metadata">

**Author:** ![preethi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/f04885/32.png) [@preethi](https://www.ruby-forum.com/u/preethi)\
**Post date:** [September 18, 2009, 1:00pm UTC](https://www.ruby-forum.com/t/rack-error/175714/3 "2009-09-18T13:00:15Z")

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Gourav T. wrote:

> I would say
> 
> [http://rack.rubyforge.org/doc/SPEC.html](http://rack.rubyforge.org/doc/SPEC.html)  
> and  
> [http://rack.rubyforge.org/doc/](http://rack.rubyforge.org/doc/)  
> will be helpful.
> 
> -Gourav
> 
> On Sep 18, 11:39�am, Preethi S. \<rails-mailing-l…@andreas-

Thanks Gourav. That was of good help!