diff --git a/CHANGES.md b/CHANGES.md
new file mode 100644
index 00000000..309aabb0
--- /dev/null
+++ b/CHANGES.md
@@ -0,0 +1,58 @@
+# Changes in OSEM 2.0
+
+Not release yet...
+
+## Update from 1.0
+
+### Multiple Schedules
+A conference can have multiple schedules now so it's easier for organizers to
+test schedules and collaborate on different versions.
+
+For this some of the existing data needs to be changed. If you update
+from 1.0 please run this rake task to move your old schedules to the
+new system.
+
+```
+bundle exec rake data:move_events_attributes RAILS_ENV=production
+```
+
+### Dropped visit/campaign tracking
+We have dropped the feature to track visits and campaigns (utm parameters)
+inside OSEM. We recommend you use [matomo](https://matomo.org/) for things
+like that. Before you update to OSEM 1.1 you should drop all the data we
+have collected.
+
+```
+bundle exec rake data:drop_all_ahoy_events RAILS_ENV=production
+```
+
+### Conference wide revision history
+There is now a conference wide revision history that will show organizers
+everything that is happening. To be able to do this we need to change old
+data.
+
+```
+bundle exec rake data:set_conference_in_versions RAILS_ENV=production
+```
+
+# Changes in OSEM 1.0
+
+[Released May 24, 2016](https://osem.io/1.0)
+
+Our first release after developing and using this app in production for
+many years. Too many changes to list, see the release announcement to
+learn what OSEM is about.
+
+https://osem.io/1.0
+
+## Update from master
+
+### Configuration through the environment
+If you have deployed OSEM from master before there is one thing you need to do
+manually. OSEM is now configured through environment variables and not through
+the config/options.yml anymore. There is a rake task to migrate your existing
+data to a .env file that OSEM will use:
+
+```
+bundle exec rake data:migrate:config2dotenv RAILS_ENV=production
+```
diff --git a/app/models/ability.rb b/app/models/ability.rb
index 23eba7a7..85fe9cf8 100644
--- a/app/models/ability.rb
+++ b/app/models/ability.rb
@@ -31,10 +31,23 @@ class Ability
       event.state == 'confirmed'
     end
 
+    can [:show, :events], Schedule do |schedule|
+      schedule.program.schedule_public
+    end
+
     # can view Commercials of confirmed Events
     can :show, Commercial, commercialable_type: 'Event', commercialable_id: Event.where(state: 'confirmed').pluck(:id)
     can [:show, :create], User
-    unless ENV['OSEM_ICHAIN_ENABLED'] == 'true'
+
+    can [:index, :show], Survey, surveyable_type: 'Conference'
+
+    # Things that are possible without ichain enabled that are **not*+ possible with ichain mode enabled.
+    if ENV['OSEM_ICHAIN_ENABLED'] != 'true'
+      # There is no reliable way for this workflow (enable not logged in users to fill out a form, then telling
+      # them to sign up once they submit) in ichain. So enable it only without ichain.
+
+      # FIXME: The following abilities need to be checked. Are they about the type of  workflow mentioned above? Or are
+      # they just here because they worked in development mode (without ichain). We are suspicious that it's the latter!
       can :show, Registration do |registration|
         registration.new_record?
       end
@@ -51,12 +64,6 @@ class Ability
       can [:new, :create], Event do |event|
         event.program.cfp_open? && event.new_record?
       end
-
-      can [:show, :events], Schedule do |schedule|
-        schedule.program.schedule_public
-      end
-
-      can [:index, :show], Survey, surveyable_type: 'Conference'
     end
   end
 
diff --git a/app/views/admin/versions/_object_desc_and_link.html.haml b/app/views/admin/versions/_object_desc_and_link.html.haml
index bd06c92a..5f81f29e 100644
--- a/app/views/admin/versions/_object_desc_and_link.html.haml
+++ b/app/views/admin/versions/_object_desc_and_link.html.haml
@@ -79,8 +79,8 @@
   = link_to (current_or_last_object_state('Event', object.event_id).try(:title) || 'deleted'),
            admin_conference_program_event_path(conference_short_title, object.event_id)
   in
-  =  link_to "Schedule #{event_schedule.schedule_id}",
-            admin_conference_schedule_path(conference_short_title, event_schedule.schedule_id)
+  =  link_to "Schedule #{version.item.schedule_id}",
+            admin_conference_schedule_path(conference_short_title, version.item.schedule_id)
 
 - when 'Schedule'
   = link_if_alive version, "Schedule #{version.item_id}",
diff --git a/lib/tasks/several_schedules.rake b/lib/tasks/several_schedules.rake
index 759951f7..9c58942e 100644
--- a/lib/tasks/several_schedules.rake
+++ b/lib/tasks/several_schedules.rake
@@ -6,8 +6,8 @@ namespace :data do
   task move_events_attributes: :environment do
     Program.all.each do |program|
       schedule = Schedule.create(program: program)
-      program.selected_schedule = schedule
-      program.save
+      program.selected_schedule = schedule unless program.selected_schedule
+      program.save!
       program.events.each do |event|
         unless event.start_time.nil? && event.room_id.nil?
           # we can not use .room as this relation has been removed
diff --git a/lib/tasks/version.rake b/lib/tasks/version.rake
index 08a0b2ec..0827e6a5 100644
--- a/lib/tasks/version.rake
+++ b/lib/tasks/version.rake
@@ -10,8 +10,12 @@ namespace :data do
         version.update_attributes(conference_id: version.item_id)
 
       elsif version.item_type == 'Event'
-        event = (version.item || version.reify || version.next.reify)
-
+        event = version.item
+        unless event || Event.find_by(id: version.item_id)
+          puts 'Not updating versions of deleted event...'
+          next
+        end
+        event ||= (version.reify || version.next.reify)
         conference_id = if event.try(:program)
                           event.program.conference_id
                         # Event had attribute conference_id before it was replaced with program_id