diff --git a/Gemfile b/Gemfile
index 9fffcadd..b627c71f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,7 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 ruby '>= 2.3.8', '< 2.4' # must be < 2.4 until we upgrade to Rails >= 4.2.8 (see https://rubyonrails.org/2017/2/21/Rails-4-2-8-has-been-released)
 
-gem 'rails', '4.1.16'
+gem 'rails', '~> 4.2'
 gem 'json_cve_2020_10663', '~> 1.0' # required until we update json >= 2.3, which we can only do once we upgrade to Rails >= 4.2 because activesupport 4.1.* depends on json ~> 1.7 (i.e < 2.0): https://rubygems.org/gems/activesupport/versions/4.1.16
 
 gem 'devise', '~> 3.4.1'
@@ -40,6 +40,7 @@ gem 'mechanize'
 gem 'prawn'
 gem 'rqrcode'
 gem 'pdfkit'
+gem 'responders'
 
 gem 'countries'
 gem 'country_select'
diff --git a/Gemfile.lock b/Gemfile.lock
index ca83c63f..7c2b4ae1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,36 +2,44 @@ GEM
   remote: https://rubygems.org/
   specs:
     Ascii85 (1.0.2)
-    actionmailer (4.1.16)
-      actionpack (= 4.1.16)
-      actionview (= 4.1.16)
+    actionmailer (4.2.11.3)
+      actionpack (= 4.2.11.3)
+      actionview (= 4.2.11.3)
+      activejob (= 4.2.11.3)
       mail (~> 2.5, >= 2.5.4)
-    actionpack (4.1.16)
-      actionview (= 4.1.16)
-      activesupport (= 4.1.16)
-      rack (~> 1.5.2)
+      rails-dom-testing (~> 1.0, >= 1.0.5)
+    actionpack (4.2.11.3)
+      actionview (= 4.2.11.3)
+      activesupport (= 4.2.11.3)
+      rack (~> 1.6)
       rack-test (~> 0.6.2)
-    actionview (4.1.16)
-      activesupport (= 4.1.16)
+      rails-dom-testing (~> 1.0, >= 1.0.5)
+      rails-html-sanitizer (~> 1.0, >= 1.0.2)
+    actionview (4.2.11.3)
+      activesupport (= 4.2.11.3)
       builder (~> 3.1)
       erubis (~> 2.7.0)
-    activemodel (4.1.16)
-      activesupport (= 4.1.16)
+      rails-dom-testing (~> 1.0, >= 1.0.5)
+      rails-html-sanitizer (~> 1.0, >= 1.0.3)
+    activejob (4.2.11.3)
+      activesupport (= 4.2.11.3)
+      globalid (>= 0.3.0)
+    activemodel (4.2.11.3)
+      activesupport (= 4.2.11.3)
       builder (~> 3.1)
-    activerecord (4.1.16)
-      activemodel (= 4.1.16)
-      activesupport (= 4.1.16)
-      arel (~> 5.0.0)
-    activesupport (4.1.16)
-      i18n (~> 0.6, >= 0.6.9)
-      json (~> 1.7, >= 1.7.7)
+    activerecord (4.2.11.3)
+      activemodel (= 4.2.11.3)
+      activesupport (= 4.2.11.3)
+      arel (~> 6.0)
+    activesupport (4.2.11.3)
+      i18n (~> 0.7)
       minitest (~> 5.1)
-      thread_safe (~> 0.1)
+      thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
     addressable (2.8.1)
       public_suffix (>= 2.0.2, < 6.0)
     afm (0.2.2)
-    arel (5.0.1.20140414130214)
+    arel (6.0.4)
     ast (2.4.2)
     atomic (1.1.101)
     avl_tree (1.2.1)
@@ -120,6 +128,8 @@ GEM
     ffi (1.12.2)
     foreman (0.84.0)
       thor (~> 0.19.1)
+    globalid (0.4.2)
+      activesupport (>= 4.2.0)
     has_scope (0.6.0)
       actionpack (>= 3.2, < 5)
       activesupport (>= 3.2, < 5)
@@ -222,28 +232,37 @@ GEM
       thor (~> 0.19.1)
       vegas (~> 0.1.11)
     racc (1.5.2)
-    rack (1.5.5)
+    rack (1.6.13)
     rack-protection (1.5.5)
       rack
     rack-test (0.6.3)
       rack (>= 1.0)
-    rails (4.1.16)
-      actionmailer (= 4.1.16)
-      actionpack (= 4.1.16)
-      actionview (= 4.1.16)
-      activemodel (= 4.1.16)
-      activerecord (= 4.1.16)
-      activesupport (= 4.1.16)
+    rails (4.2.11.3)
+      actionmailer (= 4.2.11.3)
+      actionpack (= 4.2.11.3)
+      actionview (= 4.2.11.3)
+      activejob (= 4.2.11.3)
+      activemodel (= 4.2.11.3)
+      activerecord (= 4.2.11.3)
+      activesupport (= 4.2.11.3)
       bundler (>= 1.3.0, < 2.0)
-      railties (= 4.1.16)
-      sprockets-rails (~> 2.0)
-    railties (4.1.16)
-      actionpack (= 4.1.16)
-      activesupport (= 4.1.16)
+      railties (= 4.2.11.3)
+      sprockets-rails
+    rails-deprecated_sanitizer (1.0.4)
+      activesupport (>= 4.2.0.alpha)
+    rails-dom-testing (1.0.9)
+      activesupport (>= 4.2.0, < 5.0)
+      nokogiri (~> 1.6)
+      rails-deprecated_sanitizer (>= 1.0.1)
+    rails-html-sanitizer (1.4.3)
+      loofah (~> 2.3)
+    railties (4.2.11.3)
+      actionpack (= 4.2.11.3)
+      activesupport (= 4.2.11.3)
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
     rainbow (3.1.1)
-    rake (13.0.6)
+    rake (13.1.0)
     ranked-model (0.4.0)
       activerecord (>= 3.1.12)
     rb-fsevent (0.10.2)
@@ -257,8 +276,9 @@ GEM
     render_anywhere (0.0.12)
       rails (>= 3.0.7)
     request_store (1.0.8)
-    responders (1.1.2)
-      railties (>= 3.2, < 4.2)
+    responders (2.4.1)
+      actionpack (>= 4.2.0, < 6.0)
+      railties (>= 4.2.0, < 6.0)
     rexml (3.2.5)
     rmagick (5.1.0)
       pkg-config (~> 1.4)
@@ -436,12 +456,13 @@ DEPENDENCIES
   pundit (= 0.2.1)
   pygments.rb (~> 1.1.0)
   qless
-  rails (= 4.1.16)
+  rails (~> 4.2)
   ranked-model (< 0.4.3)
   recaptcha
   redcarpet
   redis (< 4.0)
   render_anywhere
+  responders
   rmagick
   rqrcode
   rspec-rails (~> 3.0)