diff --git a/.ruby-version b/.ruby-version
index 2bf1c1ccf..005119baa 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.3.1
+2.4.1
diff --git a/.travis.yml b/.travis.yml
index f24d1cc4c..e3cfaaa1e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,7 +19,7 @@ services:
   - mysql
 language: ruby
 rvm:
-  - 2.3.1
+  - 2.4.1
 before_install:
   - sudo apt-get -qq update
   - sudo apt-get install -y curl git-core patch build-essential bison zlib1g-dev libssl-dev libxml2-dev libxml2-dev sqlite3 libsqlite3-dev autotools-dev libxslt1-dev libyaml-0-2 autoconf automake libreadline6-dev libyaml-dev libtool libgmp-dev libgdbm-dev libncurses5-dev pkg-config libffi-dev libmysqlclient-dev postfix
diff --git a/Gemfile b/Gemfile
index b8c30bea9..de130ccac 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-ruby '2.3.1'
+ruby '2.4.1'
 
 gem 'rails', '4.2.9'
 gem 'rails-observers'
diff --git a/Gemfile.lock b/Gemfile.lock
index 2278b3980..1470f97c3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -77,12 +77,12 @@ GEM
     composite_primary_keys (8.1.6)
       activerecord (~> 4.2.0)
     concurrent-ruby (1.0.5)
-    coveralls (0.8.16)
+    coveralls (0.8.21)
       json (>= 1.8, < 3)
-      simplecov (~> 0.12.0)
-      term-ansicolor (~> 1.3.0)
-      thor (~> 0.19.1)
-      tins (>= 1.6.0, < 2)
+      simplecov (~> 0.14.1)
+      term-ansicolor (~> 1.3)
+      thor (~> 0.19.4)
+      tins (~> 1.6)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     daemons (1.2.4)
@@ -154,7 +154,7 @@ GEM
     guard-symlink (0.1.1)
       guard
       guard-compat (~> 1.1)
-    hashdiff (0.3.2)
+    hashdiff (0.3.5)
     hashie (3.5.6)
     htmlentities (4.3.4)
     http (1.0.4)
@@ -260,7 +260,7 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
-    puma (3.6.0)
+    puma (3.9.1)
     rack (1.6.8)
     rack-livereload (0.3.16)
       rack
@@ -294,7 +294,7 @@ GEM
       thor (>= 0.18.1, < 2.0)
     rainbow (2.2.2)
       rake
-    raindrops (0.17.0)
+    raindrops (0.19.0)
     rake (12.0.0)
     rb-fsevent (0.9.7)
     rb-inotify (0.9.7)
@@ -349,16 +349,17 @@ GEM
     shellany (0.0.1)
     simple-rss (1.3.1)
     simple_oauth (0.3.1)
-    simplecov (0.12.0)
+    simplecov (0.14.1)
       docile (~> 1.1.0)
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
-    simplecov-html (0.10.0)
+    simplecov-html (0.10.1)
     simplecov-rcov (0.2.3)
       simplecov (>= 0.4.1)
     slack-notifier (1.5.1)
     slop (3.6.0)
-    spring (1.7.2)
+    spring (2.0.2)
+      activesupport (>= 4.2)
     spring-commands-rspec (1.0.4)
       spring (>= 0.9.1)
     sprockets (3.7.1)
@@ -371,7 +372,7 @@ GEM
     sqlite3 (1.3.11)
     telegramAPI (1.2.2)
       rest-client (~> 2.0, >= 1.7.3)
-    term-ansicolor (1.3.2)
+    term-ansicolor (1.6.0)
       tins (~> 1.0)
     test-unit (3.2.1)
       power_assert
@@ -381,7 +382,7 @@ GEM
     thor (0.19.4)
     thread_safe (0.3.6)
     tilt (2.0.5)
-    tins (1.13.0)
+    tins (1.15.0)
     twitter (5.17.0)
       addressable (~> 2.3)
       buftok (~> 0.2.0)
@@ -401,13 +402,13 @@ GEM
       unf_ext
     unf_ext (0.0.7.4)
     unicode-display_width (1.1.1)
-    unicorn (5.2.0)
+    unicorn (5.3.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
     valid_email2 (2.0.0)
       activemodel (>= 3.2)
       mail (~> 2.5)
-    webmock (2.3.2)
+    webmock (3.0.1)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
       hashdiff
@@ -500,7 +501,7 @@ DEPENDENCIES
   zendesk_api
 
 RUBY VERSION
-   ruby 2.3.1p112
+   ruby 2.4.1p111
 
 BUNDLED WITH
    1.15.1
diff --git a/app/controllers/form_controller.rb b/app/controllers/form_controller.rb
index cb3b68a9d..ce52e72dd 100644
--- a/app/controllers/form_controller.rb
+++ b/app/controllers/form_controller.rb
@@ -154,7 +154,7 @@ class FormController < ApplicationController
   private
 
   def token_gen(fingerprint)
-    crypt = ActiveSupport::MessageEncryptor.new(Setting.get('application_secret'))
+    crypt = ActiveSupport::MessageEncryptor.new(Setting.get('application_secret')[0, 32])
     fingerprint = "#{Base64.strict_encode64(Setting.get('fqdn'))}:#{Time.zone.now.to_i}:#{Base64.strict_encode64(fingerprint)}"
     Base64.strict_encode64(crypt.encrypt_and_sign(fingerprint))
   end
@@ -166,7 +166,7 @@ class FormController < ApplicationController
       return false
     end
     begin
-      crypt = ActiveSupport::MessageEncryptor.new(Setting.get('application_secret'))
+      crypt = ActiveSupport::MessageEncryptor.new(Setting.get('application_secret')[0, 32])
       result = crypt.decrypt_and_verify(Base64.decode64(token))
     rescue
       Rails.logger.info 'Invalid token for form!'
diff --git a/app/models/ticket/escalation.rb b/app/models/ticket/escalation.rb
index 68b645469..4f2f22585 100644
--- a/app/models/ticket/escalation.rb
+++ b/app/models/ticket/escalation.rb
@@ -322,23 +322,23 @@ returns
 =end
 
   def destination_time(start_time, move_minutes, biz, history_data)
-    destination_time = biz.time(move_minutes, :minutes).after(start_time)
+    local_destination_time = biz.time(move_minutes, :minutes).after(start_time)
 
     # go step by step to end of move_minutes until move_minutes is 0
     200.times.each { |_count|
 
       # check if we have pending time in the range to the destination time
-      working_minutes = period_working_minutes(start_time, destination_time, biz, history_data, true)
+      working_minutes = period_working_minutes(start_time, local_destination_time, biz, history_data, true)
       move_minutes -= working_minutes
 
       # skip if no pending time is given
       break if move_minutes <= 0
 
       # set pending destination to start time and add pending time to destination time
-      start_time       = destination_time
-      destination_time = biz.time(move_minutes, :minutes).after(start_time)
+      start_time             = local_destination_time
+      local_destination_time = biz.time(move_minutes, :minutes).after(start_time)
     }
-    destination_time
+    local_destination_time
   end
 
   # get period working minutes time in minutes
diff --git a/lib/core_ext/fixnum.rb b/lib/core_ext/integer.rb
similarity index 86%
rename from lib/core_ext/fixnum.rb
rename to lib/core_ext/integer.rb
index 71e6456c8..b3363b5f4 100644
--- a/lib/core_ext/fixnum.rb
+++ b/lib/core_ext/integer.rb
@@ -1,4 +1,4 @@
-class Fixnum
+class Integer
 
 =begin
 
diff --git a/lib/notification_factory/renderer.rb b/lib/notification_factory/renderer.rb
index f15179d96..e0c9f1229 100644
--- a/lib/notification_factory/renderer.rb
+++ b/lib/notification_factory/renderer.rb
@@ -72,7 +72,7 @@ examples how to use
     return "\#{#{object_name} / no such object}" if !object_refs
 
     # if content of method is a complex datatype, just return
-    if object_methods.empty? && object_refs.class != String && object_refs.class != Float && object_refs.class != Fixnum
+    if object_methods.empty? && object_refs.class != String && object_refs.class != Float && object_refs.class != Integer
       return "\#{#{key} / no such method}"
     end
     object_methods_s = ''