OPTION and PROPFIND request on the parent path

config/routes.rb

@@ -165,5 +165,8 @@ if Redmine::Plugin.installed? :redmine_dmsf
       end
     end
 
+    # WebDAV
+    match '/', to: lambda { |env| [405, {}, [env.to_s]] }, via: [:propfind, :options]
+    match '/dmsf', to: lambda { |env| [405, {}, [env.to_s]] }, via: [:propfind, :options]
   end
 end

lib/redmine_dmsf/webdav/custom_middleware.rb

@@ -57,7 +57,7 @@ module RedmineDmsf
         # If the URL map generated by Rack::Builder did not find a matching path,
         # it will return a 404 along with the X-Cascade header set to 'pass'.
         if (status == 404) && (headers['X-Cascade'] == 'pass')
-          @rails_app.call env # Let Rails handle the request
+          @rails_app.call env # let Rails handle the request
         else
           [status, headers, body]
         end

test/integration/webdav/dmsf_webdav_custom_middleware_test.rb

@@ -34,22 +34,22 @@ class DmsfWebdavCustomMiddlewareTest < RedmineDmsf::Test::IntegrationTest
 
   def test_options_for_root_path
     process :options, '/'
-    assert_response :not_found
+    assert_response :method_not_allowed
   end
 
   def test_options_for_dmsf_root_path
     process :options, '/dmsf'
-    assert_response :not_found
+    assert_response :method_not_allowed
   end
 
   def test_propfind_for_root_path
     process :propfind, '/'
-    assert_response :not_found
+    assert_response :method_not_allowed
   end
 
   def test_propfind_for_dmsf_root_path
     process :propfind, '/dmsf'
-    assert_response :not_found
+    assert_response :method_not_allowed
   end
 
   def test_webdav_not_enabled