You have two options:
- Upgrade your Ruby
You are running Ruby < 1.9. The currently supported version of Ruby is 2.1 and the 1.8 series is deprecated and 1.9 series is scheduled for deprecation.
- Change the version
What the commenter really meant was "use an older version of the cookbook". You can do this by specifying the -v
flag to knife or downloading an older version from the community site.