diff --git a/app/controllers/dmsf_files_controller.rb b/app/controllers/dmsf_files_controller.rb
index e7b48f9e..7b63732f 100644
--- a/app/controllers/dmsf_files_controller.rb
+++ b/app/controllers/dmsf_files_controller.rb
@@ -142,10 +142,11 @@ class DmsfFilesController < ApplicationController
           revision.disk_filename = revision.new_storage_filename
           revision.mime_type = upload.mime_type
           revision.digest = upload.digest
-          revision.file.attach(
+          revision.shared_file.attach(
             io: File.open(upload.tempfile_path),
             filename: revision.disk_filename,
-            content_type: revision.mime_type
+            content_type: revision.mime_type,
+            identify: false
           )
         end
       else
diff --git a/app/helpers/dmsf_upload_helper.rb b/app/helpers/dmsf_upload_helper.rb
index cfb5335f..0d6a9028 100644
--- a/app/helpers/dmsf_upload_helper.rb
+++ b/app/helpers/dmsf_upload_helper.rb
@@ -96,10 +96,11 @@ module DmsfUploadHelper
               a = Attachment.find_by_token(committed_file[:token])
               committed_file[:tempfile_path] = a.diskfile if a
             end
-            new_revision.file.attach(
+            new_revision.shared_file.attach(
               io: File.open(committed_file[:tempfile_path]),
               filename: new_revision.name,
-              content_type: new_revision.mime_type
+              content_type: new_revision.mime_type,
+              identify: false
             )
             file.last_revision = new_revision
             files.push file
diff --git a/db/migrate/20251015130601_active_storage_migration.rb b/db/migrate/20251015130601_active_storage_migration.rb
new file mode 100644
index 00000000..d4ec0719
--- /dev/null
+++ b/db/migrate/20251015130601_active_storage_migration.rb
@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+# Redmine plugin for Document Management System "Features"
+#
+# Karel Pičman <karel.picman@kontron.com>
+#
+# This file is part of Redmine DMSF plugin.
+#
+# Redmine DMSF plugin is free software: you can redistribute it and/or modify it under the terms of the GNU General
+# Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any
+# later version.
+#
+# Redmine DMSF plugin is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+# the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with Redmine DMSF plugin. If not, see
+# <https://www.gnu.org/licenses/>.
+
+# Migrate documents to/from Active Storage
+class ActiveStorageMigration < ActiveRecord::Migration[7.0]
+
+  # File system -> Active Storage
+  def up
+    $stdout.puts "It could be a very long process. Be patient...\n"
+    Dir.glob(DmsfFile.storage_path.join('**/*')).each do |path|
+      # Print out the currently processed directory
+      unless File.file?(path)
+        $stdout.puts path
+        next
+      end
+      # Process a file
+      disk_filename = File.basename(path)
+      DmsfFileRevision.where(disk_filename: disk_filename)
+                       .order(source_dmsf_file_revision_id: :asc)
+                       .find_each
+                       .with_index do |r, i|
+        next if r.dmsf_file.project.id != 3886 # Dry run
+
+        if i.zero?
+          r.shared_file.attach(
+            io: File.open(path),
+            filename: r.name,
+            content_type: r.mime_type,
+            identify: false
+          )
+          # Remove the original file
+          FileUtils.rm path
+          key = r.shared_file.blob.key
+          $stdout.puts "#{path} => #{File.join(key[0..1], key[2..3], key)} (#{r.shared_file.blob.filename})"
+        else
+          # The other revisions should have set the source revision
+          unless r.source_dmsf_file_revision_id
+            warn "r#{r.id}.source_dmsf_file_revision_id is null"
+          end
+        end
+      end
+    end
+    $stdout.puts 'Done'
+  end
+
+  # Active Storage -> File system
+  def down
+    n = DmsfFileRevision.all.size
+    $stdout.puts "#{n} revisions found. It could be a very long process. Be patient...\n"
+    DmsfFileRevision.find_each.with_index do |r, i|
+      $stdout.print "\r#{i * 100 / n}%"
+      next unless r.shared_file.attached?
+      next if r.dmsf_file.project.id != 3886 # Dry run
+
+      new_path = r.disk_file(search_if_not_exists: false)
+      unless File.exist?(new_path)
+        r.shared_file.open do |f|
+          FileUtils.mv f.path, new_path
+        end
+      end
+      # Remove the original file
+      r.shared_file.purge
+    end
+    $stdout.puts 'Done'
+  end
+end