How to fix the “msvcrt-ruby18.dll is missing from your computer” error message in Ruby on Rails

Here’s how to fix that annoying Ruby on Rails popup message: “The program can’t start because msvcrt-ruby18.dll is missing from your computer. Try reinstalling the program to fix this problem.”

This fix applies if you’re using cucumber on Windows.

It turns out the error message is related to the json gem that cucumber depends on. The details and solution are buried in thisthread.

To fix it, you just have to run:

gem uninstall json

followed by:

gem install json --platform=ruby

Notes:
You need to have DevKit installed for this fix: https://github.com/oneclick/rubyinstaller/wiki/Development-Kit

If you get an error when installing the new json gem, make sure a rails server or console isn't running in the background.

The offending version of json for me was 1.4.6-x86-mingw32, so you need to uninstall and install that version: gem install json --version=1.4.6 --platform=ruby

If you install new gems after you make this fix, the error message will pop-up again, so you'll have to uninstall/install the json gem again. If anyone knows a way around this, please let me know.

Anyway, I hope this fix is helpful, that error was driving me nuts!