LoadError: cannot load such file -- mime/types (LoadError)

Question

I am trying to migrate a Redmine plugin to 5.x. And then I hit this error:

LoadError: cannot load such file -- mime/types (LoadError)

The code is like:

# coding: utf-8
require 'nkf'
require 'csv'
require 'mime/types'

I tried gem install mime but the issue was still there.

Answer 1

The issue got resolved. I put mime-type in Gemfile and the issue is gone. The issue can't fixed by manually installing mime-type. This is a newbie issue.