diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index f907b11598..63fc42e266 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -411,12 +411,11 @@ class ApplicationController < ActionController::Base
     @attachments = att || []
   end
 
-  def parse_params_for_bulk_update(params)
-    attributes = (params || {}).reject {|k, v| v.blank?}
-    attributes.keys.each {|k| attributes[k] = '' if attributes[k] == 'none'}
-    if custom = attributes[:custom_field_values]
-      custom.reject! {|k, v| v.blank?}
-      custom.keys.each do |k|
+  def parse_none_to_blank(params)
+    attributes = (params || {})
+    attributes.each_key {|k| attributes[k] = '' if attributes[k] == 'none'}
+    if (custom = attributes[:custom_field_values])
+      custom.each_key do |k|
         if custom[k].is_a?(Array)
           custom[k] << '' if custom[k].delete('__none__')
         else
@@ -427,6 +426,15 @@ class ApplicationController < ActionController::Base
     attributes
   end
 
+  def parse_params_for_bulk_update(params)
+    attributes = (params || {}).reject {|k, v| v.blank?}
+    if custom = attributes[:custom_field_values]
+      custom.reject! {|k, v| v.blank?}
+    end
+
+    parse_none_to_blank(attributes)
+  end
+
   # make sure that the user is a member of the project (or admin) if project is private
   # used as a before_action for actions that do not require any particular permission on the project
   def check_project_privacy
diff --git a/app/controllers/issues_controller.rb b/app/controllers/issues_controller.rb
index 080520ef5d..d279604f65 100644
--- a/app/controllers/issues_controller.rb
+++ b/app/controllers/issues_controller.rb
@@ -561,6 +561,7 @@ class IssuesController < ApplicationController
         return false
       end
     end
+    issue_attributes = parse_none_to_blank(issue_attributes)
     @issue.safe_attributes = issue_attributes
     @priorities = IssuePriority.active
     @allowed_statuses = @issue.new_statuses_allowed_to(User.current)
diff --git a/test/functional/issues_controller_test.rb b/test/functional/issues_controller_test.rb
index 36d906fd2e..68bb9ab33b 100644
--- a/test/functional/issues_controller_test.rb
+++ b/test/functional/issues_controller_test.rb
@@ -6660,6 +6660,33 @@ class IssuesControllerTest < Redmine::ControllerTest
     assert_equal 2, issue.reload.assigned_to_id
   end
 
+  def test_update_with_value_of_none
+    @request.session[:user_id] = 2
+    issue = Issue.find(1)
+    issue.custom_field_values = {1 => 'MySQL'}
+    issue.assigned_to_id = 2
+    issue.save!
+
+    put(
+      :update,
+      params: {
+        id: issue.id,
+        issue: {
+          assigned_to_id: 'none',
+          category_id: 'none',
+          fixed_version_id: 'none',
+          custom_field_values: { 1 => '__none__' }
+        }
+      }
+    )
+
+    issue.reload
+    assert_nil issue.assigned_to
+    assert_nil issue.category
+    assert_nil issue.fixed_version
+    assert_equal '', issue.custom_field_value(1)
+  end
+
   def test_get_bulk_edit
     @request.session[:user_id] = 2
     get(:bulk_edit, :params => {:ids => [1, 3]})