diff --git a/app/controllers/codeharbor_links_controller.rb b/app/controllers/codeharbor_links_controller.rb
index ddff149f..732d897e 100644
--- a/app/controllers/codeharbor_links_controller.rb
+++ b/app/controllers/codeharbor_links_controller.rb
@@ -1,20 +1,8 @@
+# frozen_string_literal: true
+
 class CodeharborLinksController < ApplicationController
   include CommonBehavior
-  before_action :set_codeharbor_link, only: [:show, :edit, :update, :destroy]
-
-  def authorize!
-    authorize(@codeharbor_link || @codeharbor_links)
-  end
-  private :authorize!
-
-  # def index
-  #   @codeharbor_links = CodeharborLink.where(user_id: current_user.id).paginate(page: params[:page])
-  #   authorize!
-  # end
-
-  # def show
-  #   authorize!
-  # end
+  before_action :set_codeharbor_link, only: %i[show edit update destroy]
 
   def new
     @codeharbor_link = CodeharborLink.new
@@ -33,8 +21,8 @@ class CodeharborLinksController < ApplicationController
   end
 
   def update
-    update_and_respond(object: @codeharbor_link, params: codeharbor_link_params, path: @codeharbor_link.user)
     authorize!
+    update_and_respond(object: @codeharbor_link, params: codeharbor_link_params, path: @codeharbor_link.user)
   end
 
   def destroy
@@ -43,6 +31,10 @@ class CodeharborLinksController < ApplicationController
 
   private
 
+  def authorize!
+    authorize @codeharbor_link
+  end
+
   def set_codeharbor_link
     @codeharbor_link = CodeharborLink.find(params[:id])
     @codeharbor_link.user = current_user
diff --git a/app/controllers/exercises_controller.rb b/app/controllers/exercises_controller.rb
index 1421db5a..9e1c057d 100644
--- a/app/controllers/exercises_controller.rb
+++ b/app/controllers/exercises_controller.rb
@@ -108,29 +108,15 @@ class ExercisesController < ApplicationController
   end
 
   def push_proforma_xml
-    # codeharbor_link = current_user.codeharbor_link # CodeharborLink.find(params[:account_link])
-
     error = ExerciseService::PushExternal.call(
       zip: ProformaService::ExportTask.call(exercise: @exercise),
       codeharbor_link: current_user.codeharbor_link
     )
     if error.nil?
-      redirect_to exercises_path, notice: 'klappt' # t('controllers.exercise.push_external_notice', account_link: account_link.readable)
-      # redirect_to @exercise, notice: 'klappt' # t('controllers.exercise.push_external_notice', account_link: account_link.readable)
+      redirect_to exercises_path, notice: t('exercises.export_codeharbor.success')
     else
-      # logger.debug(error)
-      redirect_to exercises_path, alert: 'klappt nicht' # t('controllers.account_links.not_working', account_link: account_link.readable)
-      # redirect_to @exercise, alert: 'klappt nicht' # t('controllers.account_links.not_working', account_link: account_link.readable)
+      redirect_to exercises_path, alert: t('exercises.export_codeharbor.fail')
     end
-    # oauth2_client = OAuth2::Client.new(codeharbor_link.client_id, codeharbor_link.client_secret, url: codeharbor_link.push_url, ssl: {verify: false})
-    # oauth2token = codeharbor_link[:oauth2token]
-    # token = OAuth2::AccessToken.from_hash(oauth2_client, access_token: oauth2token)
-
-    # # xml_generator = Proforma::XmlGenerator.new
-    # xml_document = xml_generator.generate_xml(@exercise)
-    # request = token.post(codeharbor_link.push_url, body: xml_document, headers: {'Content-Type' => 'text/xml'})
-    # puts request
-    # redirect_to @exercise, notice: t('exercises.push_proforma_xml.notice', link: codeharbor_link.push_url)
   end
 
   def import_proforma_xml
@@ -138,7 +124,10 @@ class ExercisesController < ApplicationController
     tempfile.write request.body.read.force_encoding('UTF-8')
     tempfile.rewind
 
-    exercise = ProformaService::Import.call(zip: tempfile, user: user_for_oauth2_request)
+    user = user_for_oauth2_request
+    return render json: {}, status: 401 if user.nil?
+
+    exercise = ProformaService::Import.call(zip: tempfile, user: user)
     if exercise.save
       render json: {}, status: 201
     else
@@ -149,16 +138,8 @@ class ExercisesController < ApplicationController
 
   def user_for_oauth2_request
     authorization_header = request.headers['Authorization']
-    raise(status: 401, message: 'No Authorization header') if authorization_header.nil?
-
-    oauth2_token = authorization_header.split(' ')[1]
-    raise(status: 401, message: 'No token in Authorization header') if oauth2_token.nil? || oauth2_token.size.zero?
-
-    user = user_by_codeharbor_token(oauth2_token)
-
-    raise(status: 401, message: 'Unknown OAuth2 token') if user.nil?
-
-    user
+    oauth2_token = authorization_header&.split(' ')&.second
+    user_by_codeharbor_token(oauth2_token)
   end
   private :user_for_oauth2_request
 
diff --git a/app/models/codeharbor_link.rb b/app/models/codeharbor_link.rb
index 5bb1fba1..18f2da02 100644
--- a/app/models/codeharbor_link.rb
+++ b/app/models/codeharbor_link.rb
@@ -2,7 +2,6 @@
 
 class CodeharborLink < ApplicationRecord
   validates :oauth2token, presence: true
-  validates :user_id, presence: true
 
   belongs_to :user, foreign_key: :user_id, class_name: 'InternalUser'
 
diff --git a/app/services/exercise_service/push_external.rb b/app/services/exercise_service/push_external.rb
index 562ca57f..dfa54468 100644
--- a/app/services/exercise_service/push_external.rb
+++ b/app/services/exercise_service/push_external.rb
@@ -2,7 +2,7 @@
 
 module ExerciseService
   class PushExternal < ServiceBase
-    CODEHARBOR_PUSH_LINK = 'http://localhost:3001/import_exercise'
+    CODEHARBOR_PUSH_LINK = Rails.env.production? ? 'https://codeharbor.openhpi.de/import_exercise' : 'http://localhost:3001/import_exercise'
     def initialize(zip:, codeharbor_link:)
       @zip = zip
       @codeharbor_link = codeharbor_link
diff --git a/app/views/exercises/index.html.slim b/app/views/exercises/index.html.slim
index bdec864c..2b854d22 100644
--- a/app/views/exercises/index.html.slim
+++ b/app/views/exercises/index.html.slim
@@ -46,7 +46,7 @@ h1 = Exercise.model_name.human(count: 2)
                 li = link_to(t('activerecord.models.user_exercise_feedback.other'), feedback_exercise_path(exercise), class: 'dropdown-item') if policy(exercise).feedback?
                 li = link_to(t('shared.destroy'), exercise, data: {confirm: t('shared.confirm_destroy')}, method: :delete, class: 'dropdown-item') if policy(exercise).destroy?
                 li = link_to(t('.clone'), clone_exercise_path(exercise), data: {confirm: t('shared.confirm_destroy')}, method: :post, class: 'dropdown-item') if policy(exercise).clone?
-                li = link_to(t('exercises.export_codeharbor'), push_proforma_xml_exercise_path(exercise), data: {confirm: 'PUSHPUSH?'}, method: :post, class: 'dropdown-item') if policy(exercise).push_proforma_xml?
+                li = link_to(t('exercises.export_codeharbor.label'), push_proforma_xml_exercise_path(exercise), method: :post, class: 'dropdown-item') if policy(exercise).push_proforma_xml?
 
 = render('shared/pagination', collection: @exercises)
 p = render('shared/new_button', model: Exercise)
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 790e8393..6b8b243f 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -316,7 +316,10 @@ en:
       request_for_comments_sent: "Request for comments sent."
     editor_file_tree:
       file_root: Files
-    export_codeharbor: Export to Codeharbor
+    export_codeharbor:
+      label: Export to Codeharbor
+      success: Successfully pushed the exercise to CodeHarbor.
+      fail: Failed to push the exercise to CodeHarbor.
     file_form:
       hints:
         feedback_message: This message is used as a hint for failing tests.