diff --git a/app/controllers/concerns/notes_actions.rb b/app/controllers/concerns/notes_actions.rb
index 726838bb284..18fd8eb114d 100644
--- a/app/controllers/concerns/notes_actions.rb
+++ b/app/controllers/concerns/notes_actions.rb
@@ -89,7 +89,7 @@ module NotesActions
     if note.persisted?
       attrs[:valid] = true
 
-      if noteable.discussions_rendered_on_frontend?
+      if noteable.nil? || noteable.discussions_rendered_on_frontend?
         attrs.merge!(note_serializer.represent(note))
       else
         attrs.merge!(
diff --git a/app/models/note.rb b/app/models/note.rb
index d807d5ad618..1073c115630 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -300,7 +300,7 @@ class Note < ActiveRecord::Base
   end
 
   def expire_etag_cache
-    return unless noteable.discussions_rendered_on_frontend?
+    return unless noteable&.discussions_rendered_on_frontend?
 
     key = Gitlab::Routing.url_helpers.project_noteable_notes_path(
       project,
diff --git a/app/serializers/note_entity.rb b/app/serializers/note_entity.rb
index 663a9c06c40..7d50e0ff10d 100644
--- a/app/serializers/note_entity.rb
+++ b/app/serializers/note_entity.rb
@@ -14,8 +14,8 @@ class NoteEntity < API::Entities::Note
 
   expose :redacted_note_html, as: :note_html
 
-  expose :last_edited_at, if: -> (note, _) { note.is_edited? }
-  expose :last_edited_by, using: NoteUserEntity, if: -> (note, _) { note.is_edited? }
+  expose :last_edited_at, if: -> (note, _) { note.edited? }
+  expose :last_edited_by, using: NoteUserEntity, if: -> (note, _) { note.edited? }
 
   expose :current_user do
     expose :can_edit do |note|
diff --git a/spec/controllers/projects/notes_controller_spec.rb b/spec/controllers/projects/notes_controller_spec.rb
index f280c55059c..6ffe41b8608 100644
--- a/spec/controllers/projects/notes_controller_spec.rb
+++ b/spec/controllers/projects/notes_controller_spec.rb
@@ -46,10 +46,13 @@ describe Projects::NotesController do
     end
 
     context 'for a discussion note' do
-      let!(:note) { create(:discussion_note_on_issue, noteable: issue, project: project) }
+      let(:project) { create(:project, :repository) }
+      let!(:note) { create(:discussion_note_on_merge_request, project: project) }
+
+      let(:params) { request_params.merge(target_type: 'merge_request', target_id: note.noteable_id) }
 
       it 'responds with the expected attributes' do
-        get :index, request_params
+        get :index, params
 
         expect(note_json[:id]).to eq(note.id)
         expect(note_json[:discussion_html]).not_to be_nil
@@ -104,10 +107,12 @@ describe Projects::NotesController do
     end
 
     context 'for a regular note' do
-      let!(:note) { create(:note, noteable: issue, project: project) }
+      let!(:note) { create(:note_on_merge_request, project: project) }
+
+      let(:params) { request_params.merge(target_type: 'merge_request', target_id: note.noteable_id) }
 
       it 'responds with the expected attributes' do
-        get :index, request_params
+        get :index, params
 
         expect(note_json[:id]).to eq(note.id)
         expect(note_json[:html]).not_to be_nil
@@ -125,7 +130,9 @@ describe Projects::NotesController do
         note: { note: 'some note', noteable_id: merge_request.id, noteable_type: 'MergeRequest' },
         namespace_id: project.namespace,
         project_id: project,
-        merge_request_diff_head_sha: 'sha'
+        merge_request_diff_head_sha: 'sha',
+        target_type: 'merge_request',
+        target_id: merge_request.id
       }
     end