Excon::Errors::Forbidden (Expected(200) <=> Actual(403 Forbidden)

When I try to upload a picture to a "Car" object I'm denied access to S3. But the site images that are in the assets folder have displayed just fine since I added S3. The specific error that I get is this:

2015-02-17T14:40:48.459629+00:00 app[web.1]: Excon::Errors::Forbidden (Expected(200) <=> Actual(403 Forbidden)
2015-02-17T14:40:48.459630+00:00 app[web.1]: excon.error.response
2015-02-17T14:40:48.459635+00:00 app[web.1]:     "Connection"       => "close"
2015-02-17T14:40:48.459637+00:00 app[web.1]:     "Content-Type"     => "application/xml"
2015-02-17T14:40:48.459639+00:00 app[web.1]:     "Date"             => "Tue, 17 Feb 2015 14:40:48 GMT"
2015-02-17T14:40:48.459640+00:00 app[web.1]:     "Server"           => "AmazonS3"
2015-02-17T14:40:48.459632+00:00 app[web.1]:   :body          => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<Error><Code>AccessDenied</Code><Message>Access Denied</Message><RequestId>2CE306ACD51F02A1</RequestId><HostId>tKLXUAKxyDFTMExl7kE+AuVVsEJOFqXh983li6N7R2UlYDXv1Z3GJRvW5zy1XIXVs2zArp310vg=</HostId></Error>"
2015-02-17T14:40:48.459642+00:00 app[web.1]:     "x-amz-id-2"       => ""part of secret key"="

With "part of secret key" obviously redacted. I've tried creating a different user and using new keys, but that hasn't worked. Not where to go from here.

app/uploaders/picture_uploader

class PictureUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick
  process resize_to_limit: [400, 400]

  if Rails.env.production?
    storage :fog
  else
    storage :file
  end

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  # Add a white list of extensions which are allowed to be uploaded.
  def extension_white_list
    %w(jpg jpeg gif png)
  end
end

carrier_wave.rb

if Rails.env.production?
  CarrierWave.configure do |config|
    config.fog_credentials = {
      # Configuration for Amazon S3
      :provider              => 'AWS',
      :aws_access_key_id     => ENV['S3_ACCESS_KEY'],
      :aws_secret_access_key => ENV['S3_SECRET_KEY']
    }
    config.fog_directory     =  ENV['S3_BUCKET']
  end
end

I believe that's all of the relevant files, let me know if there's more to see. Not sure if specifying a region or a power user would help, doesn't seem like it would.

[EDIT: I'd default to the other answer at this point, especially if you're in a prod environment. This was a workaround that worked for me while building a breakable toy a few years back, but I agree with granting minimal permissions when security is a concern.]

I was encountering the same error, and the solution was to attach administrative access policies from the AWS Management Console:

1) Sign in to the AWS Management Console at http://aws.amazon.com/iam/

2) Click "Policies" from the Navigation Pane on the left

3) Select the "AdministratorAccess" policy

4) Click Policy Actions > Attach at the top of the page

5) Select the user associated with my S3_ACCESS_KEY, S3_SECRET_KEY, and S3_BUCKET

6) Click "Attach Policy"

Merely granting all permissions from my bucket at https://console.aws.amazon.com/s3/home was not sufficient.