# Rake doc:rails -- fails

**URL:** <https://www.ruby-forum.com/t/rake-doc-rails-fails/156353>\
**Category:** Rails\
**Created:** [December 25, 2008, 11:48am UTC](https://www.ruby-forum.com/t/rake-doc-rails-fails/156353 "2008-12-25T11:48:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![kenwei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e274bd/32.png) [@kenwei](https://www.ruby-forum.com/u/kenwei)\
**Post date:** [December 25, 2008, 11:48am UTC](https://www.ruby-forum.com/t/rake-doc-rails-fails/156353/1 "2008-12-25T11:48:58Z")

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rake doc:rails fails with:

Don’t know how to build task ‘vendor/rails/railties/CHANGELOG’

How to fix?

Rails 2.2.2, Rake 0.8.3.

Thanks,

Ken

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**Author:** ![kenwei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e274bd/32.png) [@kenwei](https://www.ruby-forum.com/u/kenwei)\
**Post date:** [December 25, 2008, 7:23pm UTC](https://www.ruby-forum.com/t/rake-doc-rails-fails/156353/2 "2008-12-25T19:23:05Z")

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Ken W. schrieb:

> rake doc:rails fails with:
> 
> Don’t know how to build task ‘vendor/rails/railties/CHANGELOG’
> 
> How to fix?

I think you have to freeze rails first:

> rake rails:freeze:gems  
> and then call  
> rake doc:rails

Martin

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<div class="post-metadata">

**Author:** ![kenwei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/e274bd/32.png) [@kenwei](https://www.ruby-forum.com/u/kenwei)\
**Post date:** [December 26, 2008, 8:16am UTC](https://www.ruby-forum.com/t/rake-doc-rails-fails/156353/3 "2008-12-26T08:16:07Z")

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Martin No wrote:

> I think you have to freeze rails first:
> 
> > rake rails:freeze:gems  
> > and then call  
> > rake doc:rails
> 
> Martin

Huh. I ran rake rails:freeze:gems and then rake doc:rails and rake  
doc:app

It all worked well.

Anyone know why we have to “freeze:gems?”

Very curious.