Completed 500 Internal Server Error in ...NameError (uninitialized constant PictureUploader::Uploader

Question

I am very new to ask the question here, hope I am following the rules correctly:

I am getting 500 server error at development env., it stated NameError with uninitialized constant for Picture uploader, BUT, most time, if I re-start the Browser (Chrome or Safari), this issue will be gone.

I am using: Rails 4.2.7.1, ruby 2.3.1p112, 'carrierwave','~> 1.0, 'mini_magick','4.3.6', rails s on puma

Is this issue possibly related to I18n locale? since I start to got this error after I have the I18n gem installed, and often happen if I changed the locales/*.yml content.

thanks you

---

Error message:

Started GET "/" for 127.0.0.1 at 2017-01-02 01:29:47 +0800
Processing by StaticPagesController#home as HTML
Completed 500 Internal Server Error in 105ms (ActiveRecord: 1.1ms)

NameError (uninitialized constant PictureUploader::Uploader70149836016940):
  activesupport (4.2.7.1) lib/active_support/inflector/methods.rb:263:in `const_get'
  activesupport (4.2.7.1) lib/active_support/inflector/methods.rb:263:in `block in constantize'
....

---

PictureUploader file is located at app folder as 'uploaders' folder, the same as assets/controllers/helpers...

app/uploaders/picure_uploader:

# app/uploaders/picture_uploader.rb
class PictureUploader < CarrierWave::Uploader::Base

  include CarrierWave::MiniMagick

  # I am still using local storage as development now
  if Rails.env.production?
  #  storage :fog
    storage :file # not yet switch to cloud/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

  # set the largest photo size
  process resize_to_limit: [800, 800]

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url
  #   # For Rails 3.1+ asset pipeline compatibility:
  #   # ActionController::Base.helpers.asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  # Process files as they are uploaded:
  # process :scale => [200, 300]
  #
  # def scale(width, height)
  #   resize_to_limit: [width, hight]
  # end

  # Create different versions of your uploaded files:
  version :thumb do
    #  process :resize_to_fit => [50, 50] # this one create different photo size
    process resize_and_pad: [50,50,:transparent,'center'] # have to be same size and transparent background, work good!
  end

  version :blog do
    # process :resize_to_pad => [400, 400, "#000000", 'Center'] # error in not finding resize_to_pad
    # process resize_and_pad: [400,400,"#CCCCCC",'center'] # this is ok
    # process resize_and_pad: [400,400,:transparent,'center'] # try to be transparent background, work good!
    process resize_to_limit: [400,400]
  end

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  def extension_white_list
    %w(jpg jpeg gif png)
  end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end

_form at form_for profile picture upload

<%= form_for([@pc_roles], html: { multipart: true }) do |f| %>

... too long ... cut it for simple reading

  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
  <span class="picture">
    <%= f.file_field :picture, accept: 'image/jpeg,image/gif,image/png' %>
    <p> photo size upto 800 in wide and tall, oversize will resized. </p>
    <%= image_tag @pc_roles.picture.url if @pc_roles.picture? %>
  </span>
<% end %>

<script type="text/javascript">
  $('#pc_role_picture').bind('change', function() {
    var size_in_megabytes = this.files[0].size/1024/1024;
    if (size_in_megabytes > 5) {
      alert('Maximum file size is 5MB. Please choose a smaller file.');
    }
  });
</script>

Model

class PcRole < ActiveRecord::Base
  belongs_to :pc_user
  mount_uploader :picture, PictureUploader
  validate  :picture_size

... cut it ... too long ... for simple reading ...

  def picture_size
    if picture.size > 5.megabytes
      errors.add(:picture, "should be less than 5MB")
    end
  end
end

btw, I also have another uploader call image_uploader.rb, in same folder of picture_uploader, under app/uploaders folder, this two are almost exactly the same:

# app/uploaders/image_uploader.rb
class ImageUploader < CarrierWave::Uploader::Base

  # Include RMagick or MiniMagick support:
  # include CarrierWave::RMagick
  include CarrierWave::MiniMagick

# Choose what kind of storage to use for this uploader:
  if Rails.env.production?
  #  storage :fog
    storage :file # not yet switch to cloud/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

  # try to fix the mobile photo rotate 90 degree issue
  def fix_exif_rotation #this is my attempted solution
    manipulate! do |img|
      img.tap(&:auto_orient)
    end
  end

  process :fix_exif_rotation


  # set the largest photo size
  process resize_to_limit: [800, 800]

  # Process files as they are uploaded:
  # process :scale => [200, 300]
  #
  # def scale(width, height)
  #   resize_to_limit: [width, hight]
  # end

  def extension_white_list
    %w(jpg jpeg gif png)
  end

end

I am using image_uploader only for TinyMCE

  <div class="field">
    <%= f.label :content %><br>
    <%= f.text_area :content, :class => "tinymce", :rows => 30, :cols => 120 %>
    <%= tinymce :uploadimage_hint => @pc_blog.id %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>

Since they are different uploaders, I am assuming it is the Picture Uploader issue.