diff --git a/app/assets/javascripts/protocols/index.js b/app/assets/javascripts/protocols/index.js
index 722c805e9..c5f010e47 100644
--- a/app/assets/javascripts/protocols/index.js
+++ b/app/assets/javascripts/protocols/index.js
@@ -425,13 +425,16 @@ var ProtocolsIndex = (function() {
   }
 
   function initdeleteDraftModal() {
-    $('.protocols-index').on('click', '#protocol-versions-modal .delete-draft', function(e) {
+    $('.protocols-index').on('click', '#protocol-versions-modal .delete-draft', function() {
       let url = this.dataset.url;
       let modal = $('#deleteDraftModal');
       $('#protocol-versions-modal').modal('hide');
       modal.modal('show');
       modal.find('form').attr('action', url);
     });
+    $('#deleteDraftModal form').on('ajax:error', function(_ev, data) {
+      HelperModule.flashAlertMsg(data.responseJSON.message, 'danger');
+    });
   }
 
   function initProtocolsioModal() {
diff --git a/app/controllers/protocols_controller.rb b/app/controllers/protocols_controller.rb
index 37ceeffed..8ad0c9923 100644
--- a/app/controllers/protocols_controller.rb
+++ b/app/controllers/protocols_controller.rb
@@ -177,6 +177,11 @@ class ProtocolsController < ApplicationController
                    protocol: @protocol.id,
                    version_number: @protocol.version_number)
     rescue ActiveRecord::RecordInvalid => e
+      flash[:error] = e.message
+      Rails.logger.error e.message
+      raise ActiveRecord::Rollback
+    rescue StandardError => e
+      flash[:error] = I18n.t('errors.general')
       Rails.logger.error e.message
       raise ActiveRecord::Rollback
     end
@@ -199,7 +204,11 @@ class ProtocolsController < ApplicationController
       redirect_to protocols_path
     rescue ActiveRecord::RecordNotDestroyed => e
       Rails.logger.error e.message
-      render json: { status: 'error' }, status: :unprocessable_entity
+      render json: { message: e.message }, status: :unprocessable_entity
+      raise ActiveRecord::Rollback
+    rescue StandardError => e
+      render json: { message: I18n.t('errors.general') }, status: :unprocessable_entity
+      Rails.logger.error e.message
       raise ActiveRecord::Rollback
     end
   end
@@ -237,7 +246,7 @@ class ProtocolsController < ApplicationController
           render json: @protocol, serializer: ProtocolSerializer, user: current_user
         end
       else
-        format.json { render json: {}, status: :unprocessable_entity }
+        format.json { render json: I18n.t('errors.general'), status: :unprocessable_entity }
       end
     end
   end
@@ -388,6 +397,8 @@ class ProtocolsController < ApplicationController
     rescue StandardError => e
       Rails.logger.error(e.message)
       Rails.logger.error(e.backtrace.join("\n"))
+      flash[:error] = I18n.t('errors.general')
+      redirect_to protocols_path
       raise ActiveRecord::Rollback
     end
   end
@@ -1105,7 +1116,7 @@ class ProtocolsController < ApplicationController
     respond_to do |format|
       if rollbacked
         format.json do
-          render json: {}, status: :bad_request
+          render json: { message: I18n.t('errors.general') }, status: :unprocessable_entity
         end
       else
         format.json do
diff --git a/app/javascript/packs/vue/protocol.js b/app/javascript/packs/vue/protocol.js
index 731014307..494bdee22 100644
--- a/app/javascript/packs/vue/protocol.js
+++ b/app/javascript/packs/vue/protocol.js
@@ -20,6 +20,10 @@ window.initProtocolComponent = () => {
     modal.find('form').attr('action', url);
   });
 
+  $('#deleteDraftModal form').on('ajax:error', function(_ev, data) {
+    HelperModule.flashAlertMsg(data.responseJSON.message, 'danger');
+  });
+
   new Vue({
     el: '#protocolContainer',
     components: {