undefined method `gsub' for nil:NilClass

[ghost]

I am getting this error while uploading the file. Is anyone here to help me?
I configure the carrierwave as mentioned.
Why it is not uploading it ?

[osadasami]

when you authorized app you got in your console:

access_token: "something"
access_token_secret: "something"
user_id: "something"

You need to write in your .bashrc or .zshrc
export APP_KEY=look at your dropbox app (something like dsdd8gfs4uc32ar)
export APP_SECRET=look at your dropbox app (something like dsdd8gfs4uc32ar)
export ACCESS_TOKEN=what you got in console, without "quotes"
export ACCESS_TOKEN_SECRET=what you got in console, without "quotes"
export USER_ID=what you got in console, without "quotes"

then in console type source
.bashrc (or .zshrc)
That will help

[osadasami]

your carrierwave.rb will look like

CarrierWave.configure do |config|
config.dropbox_app_key = ENV["APP_KEY"]
config.dropbox_app_secret = ENV["APP_SECRET"]
config.dropbox_access_token = ENV["ACCESS_TOKEN"]
config.dropbox_access_token_secret = ENV["ACCESS_TOKEN_SECRET"]
config.dropbox_user_id = ENV["USER_ID"]
config.dropbox_access_type = "app_folder" if you Choose the type of access App folder or
config.dropbox_access_type = "dropbox" if you Choose the type of access Full Dropbox
`en

[programrails]

Just put in your Gemfile this line:

gem 'carrierwave-dropbox', :git => 'https://github.com/robin850/carrierwave-dropbox.git', :tag => 'v2.0.0.rc1'