replaced flash :error key with :alert

app/controllers/devise/two_factor_authentication_controller.rb

@@ -52,7 +52,7 @@ class Devise::TwoFactorAuthenticationController < DeviseController
   def after_two_factor_fail_for(resource)
     resource.second_factor_attempts_count += 1
     resource.save
-    flash.now[:error] = find_message(:attempt_failed)
+    set_flash_message :alert, find_message(:attempt_failed), now: true
 
     if resource.max_login_attempts?
       sign_out(resource)

spec/features/two_factor_authenticatable_spec.rb

@@ -84,7 +84,7 @@ feature "User of two factor authentication" do
         fill_in "code", with: "incorrect#{rand(100)}"
         click_button "Submit"
 
-        within(".flash.error") do
+        within(".flash.alert") do
           expect(page).to have_content("Attempt failed")
         end
       end