diff --git a/app/services/proforma_service/convert_exercise_to_task.rb b/app/services/proforma_service/convert_exercise_to_task.rb
index 03bad6d8c..8907d3549 100644
--- a/app/services/proforma_service/convert_exercise_to_task.rb
+++ b/app/services/proforma_service/convert_exercise_to_task.rb
@@ -105,6 +105,9 @@ def tests
     end
 
     def xml_id_from_file(file)
+      xml_id_path = file.xml_id_path || []
+      return xml_id_path if xml_id_path&.any?
+
       type = if file.teacher_defined_assessment?
                'test'
              elsif file.reference_implementation?
@@ -112,11 +115,9 @@ def xml_id_from_file(file)
              else
                'file'
              end
-      xml_id_path_parts = file.xml_id_path&.split('/')
-      xml_id_path  = []
 
-      xml_id_path << (xml_id_path_parts&.first || "co-#{type}-#{file.id}") unless type == 'file'
-      xml_id_path << (xml_id_path_parts&.last || file.id)
+      xml_id_path << "co-#{type}-#{file.id}" unless type == 'file'
+      xml_id_path << file.id
 
       xml_id_path
     end
@@ -192,7 +193,7 @@ def task_files
     end
 
     def task_file(file)
-      file.update(xml_id_path: xml_id_from_file(file).join('/')) if file.xml_id_path.blank?
+      file.update(xml_id_path: xml_id_from_file(file)) if file.xml_id_path.blank?
 
       xml_id = xml_id_from_file(file).last
       task_file = ProformaXML::TaskFile.new(
diff --git a/app/services/proforma_service/convert_task_to_exercise.rb b/app/services/proforma_service/convert_task_to_exercise.rb
index 880915e36..8364fb9bd 100644
--- a/app/services/proforma_service/convert_task_to_exercise.rb
+++ b/app/services/proforma_service/convert_task_to_exercise.rb
@@ -97,7 +97,10 @@ def task_files
     def codeocean_file_from_task_file(file, parent_object = nil)
       extension = File.extname(file.filename)
 
-      codeocean_file = CodeOcean::File.where(context: @exercise).where('xml_id_path = ? OR xml_id_path LIKE ?', file.id, "%/#{file.id}").first_or_initialize(context: @exercise)
+      codeocean_file = CodeOcean::File
+        .where(context: @exercise)
+        .where('array_length(xml_id_path, 1) IS NOT NULL AND xml_id_path[array_length(xml_id_path, 1)] = ?', file.id)
+        .first_or_initialize(context: @exercise)
       codeocean_file.assign_attributes(
         context: @exercise,
         file_type: file_type(extension),
@@ -106,7 +109,7 @@ def codeocean_file_from_task_file(file, parent_object = nil)
         read_only: file.usage_by_lms != 'edit',
         role: extract_meta_data(@task.meta_data&.dig('meta-data'), 'files', "CO-#{file.id}", 'role'),
         path: File.dirname(file.filename).in?(['.', '']) ? nil : File.dirname(file.filename),
-        xml_id_path: (parent_object.nil? ? '' : "#{parent_object.id}/") + file.id.to_s
+        xml_id_path: (parent_object.nil? ? [file.id] : [parent_object.id, file.id])
       )
       if file.binary
         codeocean_file.native_file = FileIO.new(file.content.dup.force_encoding('UTF-8'), File.basename(file.filename))
diff --git a/db/migrate/20240903204319_add_xml_path_to_files.rb b/db/migrate/20240903204319_add_xml_path_to_files.rb
index 680624c15..80c492b6b 100644
--- a/db/migrate/20240903204319_add_xml_path_to_files.rb
+++ b/db/migrate/20240903204319_add_xml_path_to_files.rb
@@ -2,6 +2,6 @@
 
 class AddXmlPathToFiles < ActiveRecord::Migration[7.1]
   def change
-    add_column :files, :xml_id_path, :string, null: true, default: nil
+    add_column :files, :xml_id_path, :string, array: true, default: [], null: true
   end
 end
diff --git a/db/schema.rb b/db/schema.rb
index 85221e599..b53e9f9db 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -315,7 +315,7 @@
     t.string "path"
     t.integer "file_template_id"
     t.boolean "hidden_feedback", default: false, null: false
-    t.string "xml_id_path"
+    t.string "xml_id_path", default: [], array: true
     t.index ["context_id", "context_type"], name: "index_files_on_context_id_and_context_type"
   end
 
diff --git a/spec/services/proforma_service/convert_exercise_to_task_spec.rb b/spec/services/proforma_service/convert_exercise_to_task_spec.rb
index c832c832c..bf5e49b61 100644
--- a/spec/services/proforma_service/convert_exercise_to_task_spec.rb
+++ b/spec/services/proforma_service/convert_exercise_to_task_spec.rb
@@ -111,11 +111,11 @@
       end
 
       it 'sets xml_id_path to default' do
-        expect { convert_to_task.execute }.to change(file.reload, :xml_id_path).from(nil).to(file.id.to_s)
+        expect { convert_to_task.execute }.to change(file.reload, :xml_id_path).from([]).to([file.id.to_s])
       end
 
       context 'when xml_id_path is set for file' do
-        let(:file) { create(:file, xml_id_path: 'foobar') }
+        let(:file) { create(:file, xml_id_path: ['foobar']) }
 
         it 'does not change xml_path_id' do
           expect { convert_to_task.execute }.not_to change(file.reload, :xml_id_path)
@@ -204,7 +204,7 @@
 
       it 'creates a model-solution with one file with correct attributes' do
         expect(task.model_solutions.first.files.first).to have_attributes(
-          id: file.id.to_s,
+          id: file.id,
           content: file.content,
           filename: file.name_with_extension,
           used_by_grader: false,
@@ -224,7 +224,7 @@
       end
 
       context 'when reference_implementations belong to the same proforma model_solution' do
-        let(:files) { build_list(:file, 2, role: 'reference_implementation') {|file, i| file.xml_id_path = "proforma_ms/xml_id_#{i}" } }
+        let(:files) { build_list(:file, 2, role: 'reference_implementation') {|file, i| file.xml_id_path = ['proforma_ms', "xml_id_#{i}"] } }
 
         it 'creates a task with one model-solution' do
           expect(task.model_solutions).to have(1).items
@@ -267,7 +267,7 @@
 
       it 'creates a test with one file with correct attributes' do
         expect(task.tests.first.files.first).to have_attributes(
-          id: test_file.id.to_s,
+          id: test_file.id,
           content: test_file.content,
           filename: test_file.name_with_extension,
           used_by_grader: true,
@@ -294,7 +294,7 @@
       end
 
       context 'when test_files belong to the same proforma test' do
-        let(:tests) { build_list(:test_file, 2) {|file, i| file.xml_id_path = "proforma_test/xml_id_#{i}" } }
+        let(:tests) { build_list(:test_file, 2) {|file, i| file.xml_id_path = ['proforma_test', "xml_id_#{i}"] } }
 
         it 'creates a test with two file' do
           expect(task.tests.first).to have_attributes(
diff --git a/spec/services/proforma_service/convert_task_to_exercise_spec.rb b/spec/services/proforma_service/convert_task_to_exercise_spec.rb
index 400d35820..5a7e36aa0 100644
--- a/spec/services/proforma_service/convert_task_to_exercise_spec.rb
+++ b/spec/services/proforma_service/convert_task_to_exercise_spec.rb
@@ -563,9 +563,9 @@
               description: 'exercise-description')
           end
           let(:co_files) do
-            [create(:file, xml_id_path: 'id', role: 'regular_file'),
-             create(:file, xml_id_path: 'ms-id/ms-file-id', role: 'reference_implementation'),
-             create(:test_file, xml_id_path: 'test-id/test-file-id')]
+            [create(:file, xml_id_path: ['id'], role: 'regular_file'),
+             create(:file, xml_id_path: %w[ms-id ms-file-id], role: 'reference_implementation'),
+             create(:test_file, xml_id_path: %w[test-id test-file-id])]
           end
 
           it 'reuses existing file' do