diff --git a/app/views/sites/_form.haml b/app/views/sites/_form.haml
index fc88993..14a8eca 100644
--- a/app/views/sites/_form.haml
+++ b/app/views/sites/_form.haml
@@ -4,8 +4,9 @@
     %p.lead= t('.errors.help')
     %ul
       - site.errors.messages.each_pair do |attr, error|
+        - attr = attr.to_s
         - error.each do |e|
-          %li= link_to e, '#' + attr.to_s
+          %li= link_to t('activerecord.attributes.site.' + attr) + ' ' + e, '#' + attr
 
 = form_for site, html: { class: form_class(site) } do |f|
   - unless site.persisted?
diff --git a/config/initializers/bootstrap_field_with_errors.rb b/config/initializers/bootstrap_field_with_errors.rb
index 56b0a25..71b8e59 100644
--- a/config/initializers/bootstrap_field_with_errors.rb
+++ b/config/initializers/bootstrap_field_with_errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Adaptar la renderización de campos con error de Rails para que sea
 # compatible con Bootstrap4.  La forma actual rompe los inputs
 # personalizados.
@@ -5,7 +7,7 @@ ActionView::Base.field_error_proc = proc do |html_tag, _|
   return unless html_tag
 
   html = Nokogiri::HTML::DocumentFragment.parse html_tag
-  html.children.first.attributes['class'].value += ' is-invalid'
+  html&.children&.first&.attributes&.dig('class')&.value += ' is-invalid'
 
-  html.to_s.html_safe
+  html&.to_s&.html_safe || html_tag
 end