diff --git a/.rubocop.yml b/.rubocop.yml
index ff49acbde..2f9e07627 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -196,8 +196,6 @@ Style/CommentIndentation:
   Enabled: false
 Style/GlobalVars:
   Enabled: false
-Rails/TimeZone:
-  Enabled: false
 Lint/RescueException:
   Enabled: false
 Style/ClassVars:
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 949fe1bd4..ff1a0e815 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -82,9 +82,7 @@ class ApplicationController < ActionController::Base
   def session_update
     #sleep 0.6
 
-    # on many paralell requests, session got reinitialised if Time. is used, as workaround use DateTime.
-    #session[:ping] = Time.now.utc.iso8601
-    session[:ping] = DateTime.now.iso8601
+    session[:ping] = Time.zone.now.iso8601
 
     # check if remote ip need to be updated
     if !session[:remote_id] || session[:remote_id] != request.remote_ip
diff --git a/app/controllers/ical_tickets_controller.rb b/app/controllers/ical_tickets_controller.rb
index c4c1f9bd5..47993c1d5 100644
--- a/app/controllers/ical_tickets_controller.rb
+++ b/app/controllers/ical_tickets_controller.rb
@@ -125,8 +125,10 @@ class IcalTicketsController < ApplicationController
 
       event_data = {}
 
+      # rubocop:disable Rails/TimeZone
       event_data[:dtstart]     = Icalendar::Values::DateTime.new( ticket.pending_time )
       event_data[:dtend]       = Icalendar::Values::DateTime.new( ticket.pending_time )
+      # rubocop:enable Rails/TimeZone
       event_data[:summary]     = "#{ ticket.state.name } ticket: '#{ ticket.title }'"
       event_data[:description] = "T##{ ticket.number }"
 
@@ -153,8 +155,10 @@ class IcalTicketsController < ApplicationController
 
       event_data = {}
 
+      # rubocop:disable Rails/TimeZone
       event_data[:dtstart]     = Icalendar::Values::DateTime.new( ticket.escalation_time )
       event_data[:dtend]       = Icalendar::Values::DateTime.new( ticket.escalation_time )
+      # rubocop:enable Rails/TimeZone
       event_data[:summary]     = "ticket escalation: '#{ ticket.title }'"
       event_data[:description] = "T##{ ticket.number }"
 
diff --git a/app/controllers/long_polling_controller.rb b/app/controllers/long_polling_controller.rb
index c09c2cd18..a9bcbd9ae 100644
--- a/app/controllers/long_polling_controller.rb
+++ b/app/controllers/long_polling_controller.rb
@@ -29,7 +29,7 @@ class LongPollingController < ApplicationController
 
       # error handling
       if params['data']['timestamp']
-        log "request spool data > '#{Time.at( params['data']['timestamp'] )}'", client_id
+        log "request spool data > '#{Time.zone.at( params['data']['timestamp'] )}'", client_id
       else
         log 'request spool init data', client_id
       end
@@ -50,7 +50,7 @@ class LongPollingController < ApplicationController
       # send spool:sent event to client
       sleep 0.2
       log 'send spool:sent event', client_id
-      Sessions.send( client_id, { event: 'spool:sent', data: { timestamp: Time.now.utc.to_i } } )
+      Sessions.send( client_id, { event: 'spool:sent', data: { timestamp: Time.zone.now.utc.to_i } } )
     end
 
     # receive message
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index ae1eb22b1..f0d530207 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -45,7 +45,7 @@ class SessionsController < ApplicationController
     # check logon session
     logon_session_key = nil
     if params['logon_session']
-      logon_session_key = Digest::MD5.hexdigest( rand(999_999).to_s + Time.new.to_s )
+      logon_session_key = Digest::MD5.hexdigest( rand(999_999).to_s + Time.zone.now.to_s )
       #      session = ActiveRecord::SessionStore::Session.create(
       #        :session_id => logon_session_key,
       #        :data => {
diff --git a/app/models/application_model/activity_stream_base.rb b/app/models/application_model/activity_stream_base.rb
index 006edef4a..7e7d42c7d 100644
--- a/app/models/application_model/activity_stream_base.rb
+++ b/app/models/application_model/activity_stream_base.rb
@@ -29,7 +29,7 @@ returns
     role       = self.class.activity_stream_support_config[:role]
     updated_at = self.updated_at
     if force
-      updated_at = Time.new
+      updated_at = Time.zone.now
     end
     ActivityStream.add(
       o_id: self['id'],
diff --git a/app/models/job.rb b/app/models/job.rb
index d4116de65..f742675bc 100644
--- a/app/models/job.rb
+++ b/app/models/job.rb
@@ -12,7 +12,7 @@ class Job < ApplicationModel
   notify_clients_support
 
   def self.run
-    time    = Time.new
+    time    = Time.zone.now
     day_map = {
       0 => 'sun',
       1 => 'mon',
@@ -26,11 +26,11 @@ class Job < ApplicationModel
     jobs.each do |job|
 
       # only execute jobs, older then 1 min, to give admin posibility to change
-      next if job.updated_at > Time.now - 1.minutes
+      next if job.updated_at > Time.zone.now - 1.minutes
 
       # check if jobs need to be executed
       # ignore if job was running within last 10 min.
-      next if job.last_run_at && job.last_run_at > Time.now - 10.minutes
+      next if job.last_run_at && job.last_run_at > Time.zone.now - 10.minutes
 
       # check day
       next if !job.timeplan['days'].include?( day_map[time.wday] )
@@ -66,7 +66,7 @@ class Job < ApplicationModel
         ticket.save
       end
 
-      job.last_run_at = Time.now
+      job.last_run_at = Time.zone.now
       job.save
     end
     true
diff --git a/app/models/observer/ticket/close_time.rb b/app/models/observer/ticket/close_time.rb
index 3d5658918..2e6806fba 100644
--- a/app/models/observer/ticket/close_time.rb
+++ b/app/models/observer/ticket/close_time.rb
@@ -27,6 +27,6 @@ class Observer::Ticket::CloseTime < ActiveRecord::Observer
     return true if state_type.name != 'closed'
 
     # set close_time
-    record.close_time = Time.now
+    record.close_time = Time.zone.now
   end
 end
diff --git a/app/models/package.rb b/app/models/package.rb
index 0a2769c62..279f80f60 100644
--- a/app/models/package.rb
+++ b/app/models/package.rb
@@ -20,7 +20,7 @@ class Package < ApplicationModel
     end
 
     build_date = REXML::Element.new('build_date')
-    build_date.text = Time.now.utc.iso8601
+    build_date.text = Time.zone.now.iso8601
     build_host = REXML::Element.new('build_host')
     build_host.text = Socket.gethostname
 
diff --git a/app/models/scheduler.rb b/app/models/scheduler.rb
index cc2ef04ee..c7abb7088 100644
--- a/app/models/scheduler.rb
+++ b/app/models/scheduler.rb
@@ -61,10 +61,10 @@ class Scheduler < ApplicationModel
     }
   end
 
-  def self._start_job( job, runner, runner_count, try_count = 0, try_run_time = Time.now )
+  def self._start_job( job, runner, runner_count, try_count = 0, try_run_time = Time.zone.now )
     sleep 5
     begin
-      job.last_run = Time.now
+      job.last_run = Time.zone.now
       job.pid = Thread.current.object_id
       job.save
       logger.info "execute #{job.method} (runner #{runner} of #{runner_count}, try_count #{try_count})..."
@@ -83,10 +83,10 @@ class Scheduler < ApplicationModel
       try_count += 1
 
       # reset error counter if to old
-      if try_run_time + ( 60 * 5 ) < Time.now
+      if try_run_time + ( 60 * 5 ) < Time.zone.now
         try_count = 0
       end
-      try_run_time = Time.now
+      try_run_time = Time.zone.now
 
       # restart job again
       if try_run_max > try_count
@@ -122,8 +122,8 @@ class Scheduler < ApplicationModel
   end
 
   def self.check( name, time_warning = 10, time_critical = 20 )
-    time_warning_time  = Time.now - time_warning.minutes
-    time_critical_time = Time.now - time_critical.minutes
+    time_warning_time  = Time.zone.now - time_warning.minutes
+    time_critical_time = Time.zone.now - time_critical.minutes
     scheduler = Scheduler.find_by( name: name )
     if !scheduler
       puts "CRITICAL - no such scheduler jobs '#{name}'"
diff --git a/app/models/taskbar.rb b/app/models/taskbar.rb
index da5fc811a..ef3740263 100644
--- a/app/models/taskbar.rb
+++ b/app/models/taskbar.rb
@@ -9,7 +9,7 @@ class Taskbar < ApplicationModel
   private
 
   def update_last_contact
-    self.last_contact = Time.now
+    self.last_contact = Time.zone.now
   end
 
   def set_user
diff --git a/app/models/ticket/overviews.rb b/app/models/ticket/overviews.rb
index a4bfae42f..ffd5e1f98 100644
--- a/app/models/ticket/overviews.rb
+++ b/app/models/ticket/overviews.rb
@@ -206,7 +206,7 @@ returns
         sql += " #{key} IN (?)"
         bind.push value
       elsif value.class == Hash || value.class == ActiveSupport::HashWithIndifferentAccess
-        time = Time.now
+        time = Time.zone.now
         if value['area'] == 'minute'
           if value['direction'] == 'last'
             time -= value['count'].to_i * 60
diff --git a/app/models/user.rb b/app/models/user.rb
index 5a5e9ef86..1b97c6335 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -399,7 +399,7 @@ returns
 =end
 
   def update_last_login
-    self.last_login = Time.now
+    self.last_login = Time.zone.now
 
     # reset login failed
     self.login_failed = 0
diff --git a/lib/session_helper.rb b/lib/session_helper.rb
index c02c794f2..ffba462ae 100644
--- a/lib/session_helper.rb
+++ b/lib/session_helper.rb
@@ -29,10 +29,10 @@ module SessionHelper
   def self.cleanup_expired
 
     # web sessions
-    ActiveRecord::SessionStore::Session.where('request_type = ? AND updated_at < ?', 1, Time.now - 90.days ).delete_all
+    ActiveRecord::SessionStore::Session.where('request_type = ? AND updated_at < ?', 1, Time.zone.now - 90.days ).delete_all
 
     # http basic auth calls
-    ActiveRecord::SessionStore::Session.where('request_type = ? AND updated_at < ?', 2, Time.now - 2.days ).delete_all
+    ActiveRecord::SessionStore::Session.where('request_type = ? AND updated_at < ?', 2, Time.zone.now - 2.days ).delete_all
   end
 
   def self.get(id)
diff --git a/lib/sessions.rb b/lib/sessions.rb
index 746064d95..5407c5993 100644
--- a/lib/sessions.rb
+++ b/lib/sessions.rb
@@ -33,7 +33,7 @@ returns
     session_file = "#{path_tmp}/session"
 
     # collect session data
-    meta[:last_ping] = Time.new.to_i.to_s
+    meta[:last_ping] = Time.zone.now.to_i.to_s
     data = {
       user: session,
       meta: meta,
@@ -189,7 +189,7 @@ returns
     list_of_closed_sessions = []
     clients                 = Sessions.list
     clients.each { |client_id, client|
-      if !client[:meta] || !client[:meta][:last_ping] || ( client[:meta][:last_ping].to_i + idle_time_in_sec ) < Time.now.to_i
+      if !client[:meta] || !client[:meta][:last_ping] || ( client[:meta][:last_ping].to_i + idle_time_in_sec ) < Time.zone.now.to_i
         list_of_closed_sessions.push client_id
         Sessions.destory( client_id )
       end
@@ -213,7 +213,7 @@ returns
     data = get(client_id)
     return false if !data
     path = "#{@path}/#{client_id}"
-    data[:meta][:last_ping] = Time.new.to_i.to_s
+    data[:meta][:last_ping] = Time.zone.now.to_i.to_s
     content = data.to_json
     File.open( path + '/session', 'wb' ) { |file|
       file.write content
@@ -289,7 +289,7 @@ returns
 
   def self.send( client_id, data )
     path     = "#{@path}/#{client_id}/"
-    filename = "send-#{ Time.new().to_f }"
+    filename = "send-#{ Time.zone.now.to_f }"
     check    = true
     count    = 0
     while check
@@ -422,11 +422,11 @@ returns
   def self.spool_create( msg )
     path = "#{@path}/spool/"
     FileUtils.mkpath path
-    file = "#{Time.new.to_f}-#{rand(99_999)}"
+    file = "#{Time.zone.now.to_f}-#{rand(99_999)}"
     File.open( path + '/' + file, 'wb' ) { |file|
       data = {
         msg: msg,
-        timestamp: Time.now.to_i,
+        timestamp: Time.zone.now.to_i,
       }
       file.write data.to_json
     }
@@ -457,7 +457,7 @@ returns
         end
 
         # ignore message older then 48h
-        if spool['timestamp'] + (2 * 86_400) < Time.now.to_i
+        if spool['timestamp'] + (2 * 86_400) < Time.zone.now.to_i
           to_delete.push "#{path}/#{entry}"
           next
         end
@@ -568,7 +568,7 @@ returns
 
 =end
 
-  def self.thread_client(client_id, try_count = 0, try_run_time = Time.now)
+  def self.thread_client(client_id, try_count = 0, try_run_time = Time.zone.now)
     Rails.logger.debug "LOOP #{client_id} - #{try_count}"
     begin
       Sessions::Client.new(client_id)
@@ -586,10 +586,10 @@ returns
       try_count += 1
 
       # reset error counter if to old
-      if try_run_time + ( 60 * 5 ) < Time.now
+      if try_run_time + ( 60 * 5 ) < Time.zone.now
         try_count = 0
       end
-      try_run_time = Time.now
+      try_run_time = Time.zone.now
 
       # restart job again
       if try_run_max > try_count
diff --git a/lib/sessions/cache_in.rb b/lib/sessions/cache_in.rb
index ace69019f..3e4f0ae37 100644
--- a/lib/sessions/cache_in.rb
+++ b/lib/sessions/cache_in.rb
@@ -11,11 +11,11 @@ module Sessions::CacheIn
 
   def self.set( key, value, params = {} )
     if params[:expires_in]
-      @@expires_in[key]     = Time.now + params[:expires_in]
+      @@expires_in[key]     = Time.zone.now + params[:expires_in]
       @@expires_in_ttl[key] = params[:expires_in]
     end
     @@data[ key ]      = value
-    @@data_time[ key ] = Time.now
+    @@data_time[ key ] = Time.zone.now
   end
 
   def self.expired( key, params = {} )
@@ -29,14 +29,14 @@ module Sessions::CacheIn
     # set re_expire
     if params[:re_expire]
       if @@expires_in[key]
-        @@expires_in[key] = Time.now + @@expires_in_ttl[key]
+        @@expires_in[key] = Time.zone.now + @@expires_in_ttl[key]
       end
       return false
     end
 
     # check if expired
     if @@expires_in[key]
-      return true if @@expires_in[key] < Time.now
+      return true if @@expires_in[key] < Time.zone.now
       return false
     end
 
diff --git a/lib/tasks/test_browser.rake b/lib/tasks/test_browser.rake
index 21e7aa956..533960e4a 100644
--- a/lib/tasks/test_browser.rake
+++ b/lib/tasks/test_browser.rake
@@ -5,7 +5,7 @@ namespace :test do
   desc 'Start browser tests'
   task :browser, [:opts] => :environment do |_t, args|
 
-    start = Time.now()
+    start = Time.zone.now
     if !args.opts
       args.opts = ''
     end
@@ -14,7 +14,7 @@ namespace :test do
         fail 'Failed test. ' + res.inspect if !ok
       end
     }
-    puts 'All browser tests, elapsed: ' + (Time.now() - start).to_s + ' seconds'
+    puts 'All browser tests, elapsed: ' + (Time.zone.now - start).to_s + ' seconds'
 
   end
 end
diff --git a/lib/time_calculation.rb b/lib/time_calculation.rb
index cc8d37755..50898fadc 100644
--- a/lib/time_calculation.rb
+++ b/lib/time_calculation.rb
@@ -22,15 +22,15 @@ put working hours matrix and timezone in function, returns UTC working hours mat
     time_diff = 0
     if timezone
       begin
-        time_diff = Time.parse(start_time.to_s).in_time_zone(timezone).utc_offset
+        time_diff = Time.zone.parse(start_time.to_s).in_time_zone(timezone).utc_offset
      rescue Exception => e
        Rails.logger.error "Can't fine tomezone #{timezone}"
        Rails.logger.error e.inspect
        Rails.logger.error e.backtrace
       end
     end
-    beginning_of_workday = Time.parse("1977-10-27 #{config['beginning_of_workday']}")
-    end_of_workday       = Time.parse("1977-10-27 #{config['end_of_workday']}") - 3600
+    beginning_of_workday = Time.zone.parse("1977-10-27 #{config['beginning_of_workday']}")
+    end_of_workday       = Time.zone.parse("1977-10-27 #{config['end_of_workday']}") - 3600
     config_ok = false
     working_hours = {}
     [:Mon, :Tue, :Wed, :Thu, :Fri, :Sat, :Sun].each {|day|
@@ -43,7 +43,7 @@ put working hours matrix and timezone in function, returns UTC working hours mat
 
       config_ok = true
       (0..23).each {|hour|
-        time = Time.parse("1977-10-27 #{hour}:00:00")
+        time = Time.zone.parse("1977-10-27 #{hour}:00:00")
         if time >= beginning_of_workday && time <= end_of_workday
           working_hours[day].push true
         else
@@ -116,10 +116,10 @@ put working hours matrix and timezone in function, returns UTC working hours mat
 
   def self.business_time_diff(start_time, end_time, config = nil, timezone = '')
     if start_time.class == String
-      start_time  = Time.parse( start_time.to_s + 'UTC' )
+      start_time  = Time.zone.parse( start_time.to_s + 'UTC' )
     end
     if end_time.class == String
-      end_time = Time.parse( end_time.to_s + 'UTC' )
+      end_time = Time.zone.parse( end_time.to_s + 'UTC' )
     end
 
     # if no config is given, just return calculation directly
@@ -236,7 +236,7 @@ put working hours matrix and timezone in function, returns UTC working hours mat
 
   def self.dest_time(start_time, diff_in_min, config = nil, timezone = '')
     if start_time.class == String
-      start_time = Time.parse( start_time.to_s + ' UTC' )
+      start_time = Time.zone.parse( start_time.to_s + ' UTC' )
     end
 
     return start_time if diff_in_min == 0
diff --git a/script/websocket-server.rb b/script/websocket-server.rb
index 87454828d..1c9937ca6 100755
--- a/script/websocket-server.rb
+++ b/script/websocket-server.rb
@@ -95,7 +95,7 @@ EventMachine.run {
       if !@clients.include? client_id
         @clients[client_id] = {
           websocket: ws,
-          last_ping: Time.new,
+          last_ping: Time.zone.now,
           error_count: 0,
         }
       end
@@ -139,7 +139,7 @@ EventMachine.run {
 
         # error handling
         if data['timestamp']
-          log 'notice', "request spool data > '#{Time.at(data['timestamp'])}'", client_id
+          log 'notice', "request spool data > '#{Time.zone.at(data['timestamp'])}'", client_id
         else
           log 'notice', 'request spool with init data', client_id
         end
@@ -164,7 +164,7 @@ EventMachine.run {
 
         # send spool:sent event to client
         log 'notice', 'send spool:sent event', client_id
-        @clients[client_id][:websocket].send( '[{"event":"spool:sent","data":{"timestamp":' + Time.now.utc.to_i.to_s + '}}]' )
+        @clients[client_id][:websocket].send( '[{"event":"spool:sent","data":{"timestamp":' + Time.zone.now.to_i.to_s + '}}]' )
       end
 
       # get session
@@ -175,7 +175,7 @@ EventMachine.run {
         # remember ping, send pong back
       elsif data['action'] == 'ping'
         Sessions.touch(client_id)
-        @clients[client_id][:last_ping] = Time.now
+        @clients[client_id][:last_ping] = Time.zone.now
         @clients[client_id][:websocket].send( '[{"action":"pong"}]' )
 
         # broadcast
@@ -298,7 +298,7 @@ EventMachine.run {
     # close unused web socket sessions
     @clients.each { |client_id, client|
 
-      next if ( client[:last_ping] + idle_time_in_sec ) >= Time.now
+      next if ( client[:last_ping] + idle_time_in_sec ) >= Time.zone.now
 
       log 'notice', 'closing idle websocket connection', client_id
 
@@ -324,8 +324,8 @@ EventMachine.run {
     if !@options[:v]
       return if level == 'debug'
     end
-    puts "#{Time.now}:client(#{ client_id }) #{ data }"
-    #    puts "#{Time.now}:#{ level }:client(#{ client_id }) #{ data }"
+    puts "#{Time.zone.now}:client(#{ client_id }) #{ data }"
+    #    puts "#{Time.zone.now}:#{ level }:client(#{ client_id }) #{ data }"
   end
 
 }