diff --git a/Gemfile b/Gemfile
index 72faacf..3be2367 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,14 +3,14 @@ source 'https://rubygems.org'
 gemspec
 
 group :test do
-  gem 'activerecord', '~> 3.0'
+  gem 'activerecord', '~> 6.1'
   gem "sqlite3", "~> 1.3.5"
   gem "bson_ext", "~> 1.3"
   gem "capybara", "~> 1.1.0"
   gem 'shoulda', '~> 2.11.3'
   gem 'mocha', '~> 0.13.0'
   gem 'factory_girl_rails', '~> 1.2'
-  gem 'nokogiri', '< 1.6.0', :platforms => :ruby_18
+  gem 'nokogiri'
   gem 'timecop'
   gem 'railties'
   gem 'actionmailer'
diff --git a/VERSION b/VERSION
index a1dad2a..267577d 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.3.23
+0.4.1
diff --git a/app/controllers/devise/checkga_controller.rb b/app/controllers/devise/checkga_controller.rb
index 2a814f0..a81fad0 100644
--- a/app/controllers/devise/checkga_controller.rb
+++ b/app/controllers/devise/checkga_controller.rb
@@ -1,6 +1,6 @@
 class Devise::CheckgaController < Devise::SessionsController
-  prepend_before_filter :devise_resource, :only => [:show]
-  prepend_before_filter :require_no_authentication, :only => [ :show, :update ]
+  prepend_before_action :devise_resource, only: [:show]
+  prepend_before_action :require_no_authentication, only: [ :show, :update ]
 
   include Devise::Controllers::Helpers
 
diff --git a/app/controllers/devise/displayqr_controller.rb b/app/controllers/devise/displayqr_controller.rb
index fa86d80..d7dfd79 100644
--- a/app/controllers/devise/displayqr_controller.rb
+++ b/app/controllers/devise/displayqr_controller.rb
@@ -1,5 +1,6 @@
 class Devise::DisplayqrController < DeviseController
-  prepend_before_filter :authenticate_scope!, :only => [:show, :update, :refresh]
+  layout :dynamic_layout
+  prepend_before_action :authenticate_scope!, only: [:show, :update, :refresh]
 
   include Devise::Controllers::Helpers
 
@@ -17,13 +18,19 @@ def show
   def update
     if resource.gauth_tmp != params[resource_name]['tmpid'] || !resource.validate_token(params[resource_name]['gauth_token'].to_i)
       set_flash_message(:error, :invalid_token)
-      redirect_to action: :show and return
+      render :show and return
     end
 
     if resource.set_gauth_enabled(params[resource_name]['gauth_enabled'])
       set_flash_message :notice, (resource.gauth_enabled? ? :enabled : :disabled)
       sign_in scope, resource, :bypass => true
-      redirect_to stored_location_for(scope) || after_sign_in_path_for(resource)
+      if params[resource_name]['invalidate_session'] == '1'
+        sign_out resource
+        redirect_to new_user_session_path
+      else
+        redirect_to stored_location_for(scope) || after_sign_in_path_for(resource)
+        flash[:notice] = 'Congratulations! You are now registered for 2-factor authentication. You will be required to enter the code next time you log in.' if resource.is_a?(User)
+      end
     else
       render :show
     end
@@ -60,4 +67,12 @@ def resource_params
   def strong_parameters_enabled?
     defined?(ActionController::StrongParameters)
   end
+
+  def dynamic_layout
+    if resource.is_a?(User)
+      'application'
+    elsif resource.is_a?(SaasAdmin)
+      'k2admin'
+    end
+  end
 end
diff --git a/devise_google_authenticator.gemspec b/devise_google_authenticator.gemspec
index a0a71d5..78093b5 100644
--- a/devise_google_authenticator.gemspec
+++ b/devise_google_authenticator.gemspec
@@ -2,7 +2,7 @@ $LOAD_PATH.unshift File.expand_path('../lib', __FILE__)
 
 Gem::Specification.new do |s|
   s.name = "devise_google_authenticator"
-  s.version = "0.3.23"
+  s.version = "0.4.1"
   s.authors = ["Christian Frichot"]
   s.date = "2015-02-08"
   s.description = "Devise Google Authenticator Extension, for adding Google's OTP to your Rails apps!"
@@ -25,10 +25,10 @@ Gem::Specification.new do |s|
     # removed the following to try and get past this bundle update not finding compatible versions for gem issue
     # 'actionmailer' => '>= 3.0',
     #'actionmailer' => '~> 3.2',# '>= 3.2.12',
-    'devise' => '~> 3.2',
-    'rotp'   => '~> 1.6'
+    'devise'  => '~> 4.2',
+    'rotp'    => '~> 1.6',
+    'rqrcode' => '>= 2'
   }.each do |lib, version|
     s.add_runtime_dependency(lib, *version)
   end
-
 end
diff --git a/lib/devise_google_authenticatable/controllers/helpers.rb b/lib/devise_google_authenticatable/controllers/helpers.rb
index 61ade7a..62a668b 100644
--- a/lib/devise_google_authenticatable/controllers/helpers.rb
+++ b/lib/devise_google_authenticatable/controllers/helpers.rb
@@ -1,24 +1,19 @@
+require 'rqrcode'
+require 'base64'
+
 module DeviseGoogleAuthenticator
   module Controllers # :nodoc:
     module Helpers # :nodoc:
       def google_authenticator_qrcode(user, qualifier=nil, issuer=nil)
-        username = username_from_email(user.email)
-        app = user.class.ga_appname || Rails.application.class.parent_name
-        data = "otpauth://totp/#{otpauth_user(username, app, qualifier)}?secret=#{user.gauth_secret}"
-        data << "&issuer=#{issuer}" if !issuer.nil?
-        data = Rack::Utils.escape(data)
-        url = "https://chart.googleapis.com/chart?chs=200x200&chld=M|0&cht=qr&chl=#{data}"
-        return image_tag(url, :alt => 'Google Authenticator QRCode')
-      end
+        data = "otpauth://totp/#{user.email}?secret=#{user.gauth_secret}"
+        data << "&issuer=#{issuer}" unless issuer.nil?
 
-      def otpauth_user(username, app, qualifier=nil)
-        "#{username}@#{app}#{qualifier}"
-      end
+        qrcode = RQRCode::QRCode.new(data, level: :m, mode: :byte_8bit)
+        png = qrcode.as_png(fill: 'white', color: 'black', border_modules: 1, module_px_size: 4)
+        url = "data:image/png;base64,#{Base64.encode64(png.to_s).strip}"
 
-      def username_from_email(email)
-        (/^(.*)@/).match(email)[1]
+        return image_tag(url, alt: 'Google Authenticator QRCode')
       end
-
     end
   end
 end
diff --git a/lib/devise_google_authenticatable/models/google_authenticatable.rb b/lib/devise_google_authenticatable/models/google_authenticatable.rb
index b512f5f..04ea32d 100644
--- a/lib/devise_google_authenticatable/models/google_authenticatable.rb
+++ b/lib/devise_google_authenticatable/models/google_authenticatable.rb
@@ -21,11 +21,11 @@ def get_qr
 
         def set_gauth_enabled(param)
           #self.update_without_password(params[gauth_enabled])
-          self.update_attributes(:gauth_enabled => param)
+          self.update(:gauth_enabled => param)
         end
 
         def assign_tmp
-          self.update_attributes(:gauth_tmp => ROTP::Base32.random_base32(32), :gauth_tmp_datetime => DateTime.now)
+          self.update(:gauth_tmp => ROTP::Base32.random_base32(32), :gauth_tmp_datetime => DateTime.now)
           self.gauth_tmp
         end
 
diff --git a/lib/devise_google_authenticatable/rails.rb b/lib/devise_google_authenticatable/rails.rb
index 7567d48..b68977e 100644
--- a/lib/devise_google_authenticatable/rails.rb
+++ b/lib/devise_google_authenticatable/rails.rb
@@ -1,8 +1,7 @@
 module DeviseGoogleAuthenticator
   class Engine < ::Rails::Engine # :nodoc:
-    ActionDispatch::Callbacks.to_prepare do
+    ActiveSupport::Reloader.to_prepare do
       DeviseGoogleAuthenticator::Patches.apply
     end
-
   end
 end
diff --git a/lib/devise_google_authenticator.rb b/lib/devise_google_authenticator.rb
index 9cd1b3e..b2c590f 100644
--- a/lib/devise_google_authenticator.rb
+++ b/lib/devise_google_authenticator.rb
@@ -16,7 +16,7 @@ module Devise # :nodoc:
 	@@ga_remembertime = 1.month
 
 	mattr_accessor :ga_appname
-	@@ga_appname = Rails.application.class.parent_name
+	@@ga_appname = Rails.application.class.module_parent_name
 
 	mattr_accessor :ga_bypass_signup
 	@@ga_bypass_signup = false
@@ -36,4 +36,4 @@ module DeviseGoogleAuthenticator
 require 'devise_google_authenticatable/controllers/helpers'
 ActionView::Base.send :include, DeviseGoogleAuthenticator::Controllers::Helpers
 
-Devise.add_module :google_authenticatable, :controller => :google_authenticatable, :model => 'devise_google_authenticatable/models/google_authenticatable', :route => :displayqr
\ No newline at end of file
+Devise.add_module :google_authenticatable, :controller => :google_authenticatable, :model => 'devise_google_authenticatable/models/google_authenticatable', :route => :displayqr
diff --git a/test/integration/gauth_test.rb b/test/integration/gauth_test.rb
index 92bc477..1871fa3 100644
--- a/test/integration/gauth_test.rb
+++ b/test/integration/gauth_test.rb
@@ -28,7 +28,7 @@ def teardown
 
   test 'a new user should be able to sign in without using their token' do
     create_full_user
-    User.find_by_email("fulluser@test.com").update_attributes(:gauth_enabled => 0) # force this off - unsure why sometimes it flicks on possible race condition
+    User.find_by(email: "fulluser@test.com").update(:gauth_enabled => 0) # force this off - unsure why sometimes it flicks on possible race condition
 
     visit new_user_session_path
     fill_in 'user_email', :with => 'fulluser@test.com'
@@ -40,7 +40,7 @@ def teardown
   test 'a new user should be able to sign in and change their qr code to enabled' do
     # sign_in_as_user
     create_full_user
-    User.find_by_email("fulluser@test.com").update_attributes(:gauth_enabled => 0) # force this off - unsure why sometimes it flicks on possible race condition
+    User.find_by(email: "fulluser@test.com").update(:gauth_enabled => 0) # force this off - unsure why sometimes it flicks on possible race condition
     visit new_user_session_path
     fill_in 'user_email', :with => 'fulluser@test.com'
     fill_in 'user_password', :with => '123456'
@@ -59,7 +59,7 @@ def teardown
 
   test 'a new user should be able to sign in change their qr to enabled and be prompted for their token' do
     create_full_user
-    User.find_by_email("fulluser@test.com").update_attributes(:gauth_enabled => 0) # force this off - unsure why sometimes it flicks on possible race condition
+    User.find_by(email: "fulluser@test.com").update(:gauth_enabled => 0) # force this off - unsure why sometimes it flicks on possible race condition
     visit new_user_session_path
     fill_in 'user_email', :with => 'fulluser@test.com'
     fill_in 'user_password', :with => '123456'
@@ -179,4 +179,4 @@ def teardown
 
     Timecop.return
   end
-end
\ No newline at end of file
+end
diff --git a/test/rails_app/app/controllers/posts_controller.rb b/test/rails_app/app/controllers/posts_controller.rb
index c73d70f..201f691 100644
--- a/test/rails_app/app/controllers/posts_controller.rb
+++ b/test/rails_app/app/controllers/posts_controller.rb
@@ -59,7 +59,7 @@ def update
     @post = Post.find(params[:id])
 
     respond_to do |format|
-      if @post.update_attributes(params[:post])
+      if @post.update(params[:post])
         format.html { redirect_to @post, notice: 'Post was successfully updated.' }
         format.json { head :ok }
       else