"msvcrt-ruby18.dll was not found" with Ruby

Question

When I try to run even simple rails commands such as:

rails -h

I get a popup error after a few seconds that says:

ruby.exe - Unable To Locate Component

This application has failed to start because msvcrt-ruby18.dll was not found. Re-installing the application may fix the problem.

I am running:

• Windows XP (yes I know I should attempt ruby on a Windows machine).
• Ruby 1.9.1p378 [i386-mingw32].
• Have updated all my gems to latest versions (as of 14-July-2010).

Is there a way I can test what is making this error? Does anyone know what it could mean?

I have found that in my ruby19/bin folder there is msvcrt-ruby191.dll but there is no msvcrt-ruby18.dll anywhere. Why would it be looking for this anyway if I'm using ruby 1.9?

Answer 1

The current release version 1.1.5 of Mongrel is incompatible with Ruby 1.9 and throws this error when it is run. It's easy to solve - just make sure Rubygems is up-to-date:

gem update --system

Then install the new pre-release version of Mongrel:

gem install mongrel --pre

---

Alternatively, if this isn't caused by Mongrel, you can try installing the DevKit, then try this:

gem install *gemname* --platform=ruby

This forces compilation of the extension from source using DevKit and works with most of the major gems I've tried.