diff --git a/app/services/interactors/change_effort_event.rb b/app/services/interactors/change_effort_event.rb
index a9ea27c8b..1fcffcd58 100644
--- a/app/services/interactors/change_effort_event.rb
+++ b/app/services/interactors/change_effort_event.rb
@@ -17,11 +17,13 @@ def initialize(args)
     end
 
     def perform!
-      existing_start_time = effort.start_time
-      effort.event = new_event
-      effort.start_time = existing_start_time
-      split_times.each { |st| st.split = splits_by_distance[st.distance_from_start] }
-      save_changes
+      unless errors.present?
+        existing_start_time = effort.start_time
+        effort.event = new_event
+        effort.start_time = existing_start_time
+        split_times.each { |st| st.split = splits_by_distance[st.distance_from_start] }
+        save_changes
+      end
       Interactors::Response.new(errors, response_message)
     end
 
@@ -58,9 +60,9 @@ def response_message
     end
 
     def verify_compatibility
-      raise ArgumentError, "#{effort} cannot be assigned to #{new_event} because distances do not coincide" unless split_times.all? { |st| distances.include?(st.distance_from_start) }
-      raise ArgumentError, "#{effort} cannot be assigned to #{new_event} because sub splits do not coincide" unless split_times.all? { |st| splits_by_distance[st.distance_from_start].sub_split_bitkeys.include?(st.bitkey) }
-      raise ArgumentError, "#{effort} cannot be assigned to #{new_event} because laps exceed maximum required" unless split_times.all? { |st| maximum_lap >= st.lap }
+      errors << distance_mismatch_error(effort, new_event) and return unless split_times.all? { |st| distances.include?(st.distance_from_start) }
+      errors << sub_split_mismatch_error(effort, new_event) and return unless split_times.all? { |st| splits_by_distance[st.distance_from_start].sub_split_bitkeys.include?(st.bitkey) }
+      errors << lap_mismatch_error(effort, new_event) unless split_times.all? { |st| maximum_lap >= st.lap }
     end
   end
 end
diff --git a/app/services/interactors/change_event_course.rb b/app/services/interactors/change_event_course.rb
new file mode 100644
index 000000000..e0ceae82f
--- /dev/null
+++ b/app/services/interactors/change_event_course.rb
@@ -0,0 +1,65 @@
+module Interactors
+  class ChangeEventCourse
+    include Interactors::Errors
+
+    def self.perform!(args)
+      new(args).perform!
+    end
+
+    def initialize(args)
+      ArgsValidator.validate(params: args, required: [:event, :new_course], exclusive: [:event, :new_course], class: self.class)
+      @event = args[:event]
+      @new_course = args[:new_course]
+      @old_course ||= event.course
+      @split_times ||= event.split_times
+      @errors = []
+      verify_compatibility
+    end
+
+    def perform!
+      unless errors.present?
+        event.course = new_course
+        event.splits = new_course.splits
+        split_times.each { |st| st.split = splits_by_distance[st.distance_from_start] }
+        save_changes
+      end
+      Interactors::Response.new(errors, response_message)
+    end
+
+    private
+
+    attr_reader :event, :new_course, :split_times, :errors
+
+    def save_changes
+      ActiveRecord::Base.transaction do
+        event.save(validate: false) if event.changed?
+        split_times.each { |st| save_split_time(st) }
+        errors << resource_error_object(event) unless event.valid?
+        raise ActiveRecord::Rollback if errors.present?
+      end
+    end
+
+    def save_split_time(st)
+      if st.changed?
+        errors << resource_error_object(split_time) unless st.save
+      end
+    end
+
+    def distances
+      @distances ||= splits_by_distance.keys.to_set
+    end
+
+    def splits_by_distance
+      @splits_by_distance ||= new_course.splits.index_by(&:distance_from_start)
+    end
+
+    def response_message
+      errors.present? ? "#{event.name} could not be changed to #{new_course.name}. " : "#{event.name} was changed to #{new_course.name}. "
+    end
+
+    def verify_compatibility
+      errors << distance_mismatch_error(event, new_course) and return unless split_times.all? { |st| distances.include?(st.distance_from_start) }
+      errors << sub_split_mismatch_error(event, new_course) unless split_times.all? { |st| splits_by_distance[st.distance_from_start].sub_split_bitkeys.include?(st.bitkey) }
+    end
+  end
+end
diff --git a/app/services/interactors/errors.rb b/app/services/interactors/errors.rb
index ab13d0850..654fe2a2d 100644
--- a/app/services/interactors/errors.rb
+++ b/app/services/interactors/errors.rb
@@ -10,6 +10,21 @@ def active_record_error(exception)
        detail: {exception: exception}}
     end
 
+    def distance_mismatch_error(child, new_parent)
+      {title: 'Distances do not match',
+       detail: {messages: ["#{child} cannot be assigned to #{new_parent} because distances do not coincide"]}}
+    end
+
+    def lap_mismatch_error(child, new_parent)
+      {title: 'Distances do not match',
+       detail: {messages: ["#{child} cannot be assigned to #{new_parent} because laps exceed maximum required"]}}
+    end
+
+    def sub_split_mismatch_error(child, new_parent)
+      {title: 'Distances do not match',
+       detail: {messages: ["#{child} cannot be assigned to #{new_parent} because sub splits do not coincide"]}}
+    end
+
     def mismatched_organization_error(old_event_group, new_event_group)
       {title: 'Event group organizations do not match',
        detail: {messages: ["The event cannot be updated because #{old_event_group} is organized under #{old_event_group.organization}, but #{new_event_group} is organized under #{new_event_group.organization}"]}}
diff --git a/spec/services/interactors/change_effort_event_spec.rb b/spec/services/interactors/change_effort_event_spec.rb
index 4edf9ef36..da19b33aa 100644
--- a/spec/services/interactors/change_effort_event_spec.rb
+++ b/spec/services/interactors/change_effort_event_spec.rb
@@ -7,7 +7,7 @@
     let(:effort) { build_stubbed(:effort) }
     let(:new_event) { build_stubbed(:event) }
 
-    it 'initializes when provided with an effort and a new event_id' do
+    it 'initializes when provided with an effort and a new_event' do
       expect { subject }.not_to raise_error
     end
 
@@ -103,20 +103,26 @@
         split = new_event.ordered_splits.second
         split.update(distance_from_start: split.distance_from_start - 1)
         new_event.reload
-        expect { subject }.to raise_error(/distances do not coincide/)
+        response = subject.perform!
+        expect(response).not_to be_successful
+        expect(response.errors.first[:detail][:messages]).to include(/distances do not coincide/)
       end
 
       it 'raises an error if sub_splits do not coincide' do
         split = new_event.ordered_splits.second
         split.update(sub_split_bitmap: 1)
         new_event.reload
-        expect { subject }.to raise_error(/sub splits do not coincide/)
+        response = subject.perform!
+        expect(response).not_to be_successful
+        expect(response.errors.first[:detail][:messages]).to include(/sub splits do not coincide/)
       end
 
       it 'raises an error if laps are out of range' do
         split_time = effort.ordered_split_times.last
         split_time.update(lap: 2)
-        expect { subject }.to raise_error(/laps exceed maximum required/)
+        response = subject.perform!
+        expect(response).not_to be_successful
+        expect(response.errors.first[:detail][:messages]).to include(/laps exceed maximum required/)
       end
     end
 
diff --git a/spec/services/interactors/change_event_course_spec.rb b/spec/services/interactors/change_event_course_spec.rb
new file mode 100644
index 000000000..26376a7ac
--- /dev/null
+++ b/spec/services/interactors/change_event_course_spec.rb
@@ -0,0 +1,105 @@
+require 'rails_helper'
+
+RSpec.describe Interactors::ChangeEventCourse do
+  subject { Interactors::ChangeEventCourse.new(event: event, new_course: new_course) }
+
+  describe '#initialization' do
+    let(:event) { build_stubbed(:event) }
+    let(:new_course) { build_stubbed(:course) }
+
+    it 'initializes when provided with an event and a new course_id' do
+      expect { subject }.not_to raise_error
+    end
+
+    context 'if no event is provided' do
+      let(:event) { nil }
+
+      it 'raises an error' do
+        expect { subject }.to raise_error(/must include event/)
+      end
+    end
+
+    context 'if no new_course is provided' do
+      let(:new_course) { nil }
+
+      it 'raises an error' do
+        expect { subject }.to raise_error(/must include new_course/)
+      end
+    end
+  end
+
+  describe '#perform!' do
+    let(:event) { create(:event, course: old_course) }
+    let!(:old_course) { create(:course, splits: old_splits) }
+    let(:old_split_1) { create(:start_split) }
+    let(:old_split_2) { create(:split, distance_from_start: 10000) }
+    let(:old_split_3) { create(:split, distance_from_start: 20000) }
+    let(:old_splits) { [old_split_1, old_split_2, old_split_3] }
+    let!(:efforts) { create_list(:effort, 2, event: event) }
+
+    context 'when the new course has splits with the same distances as the old' do
+      let(:new_course) { create(:course, splits: new_splits) }
+      let(:new_split_1) { create(:start_split) }
+      let(:new_split_2) { create(:split, distance_from_start: old_course.ordered_splits.second.distance_from_start) }
+      let(:new_split_3) { create(:split, distance_from_start: old_course.ordered_splits.third.distance_from_start) }
+      let(:new_split_4) { create(:split, distance_from_start: new_split_3.distance_from_start + 10000) }
+      let(:new_splits) { [new_split_1, new_split_2, new_split_3, new_split_4] }
+
+      before do
+        FactoryBot.reload
+        old_course.reload
+        new_course.reload
+        event.splits << old_course.splits
+        create_split_times_for_event
+      end
+
+      it 'updates the event course_id to the id of the provided course' do
+        expect(event.course_id).not_to eq(new_course.id)
+        response = subject.perform!
+        expect(event.course_id).to eq(new_course.id)
+        expect(response).to be_successful
+        expect(response.message).to match(/was changed to/)
+      end
+
+      it 'changes the split_ids of event split_times to the corresponding split_ids of the new course' do
+        sub_splits = new_course.sub_splits.first(efforts.first.split_times.size)
+        efforts.each do |effort|
+          effort.reload
+          expect(effort.split_times.map(&:sub_split)).not_to match_array(sub_splits)
+        end
+        subject.perform!
+        efforts.each do |effort|
+          effort.reload
+          expect(effort.split_times.map(&:sub_split)).to match_array(sub_splits)
+        end
+      end
+
+      it 'returns an unsuccessful response with errors if distances do not coincide' do
+        split = new_course.ordered_splits.second
+        split.update(distance_from_start: split.distance_from_start - 1)
+        new_course.reload
+        response = subject.perform!
+        expect(response).not_to be_successful
+        expect(response.errors.first[:detail][:messages]).to include(/distances do not coincide/)
+      end
+
+      it 'raises an error if sub_splits do not coincide' do
+        split = new_course.ordered_splits.second
+        split.update(sub_split_bitmap: 1)
+        new_course.reload
+        response = subject.perform!
+        expect(response).not_to be_successful
+        expect(response.errors.first[:detail][:messages]).to include(/sub splits do not coincide/)
+      end
+    end
+
+    def create_split_times_for_event
+      time_points = event.required_time_points
+      efforts.each do |effort|
+        time_points.each_with_index do |time_point, i|
+          create(:split_time, time_point: time_point, effort: effort, time_from_start: i * 1000)
+        end
+      end
+    end
+  end
+end