diff --git a/Gemfile.lock b/Gemfile.lock
index 5010fd59..de61634c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -30,35 +30,35 @@ GEM
   specs:
     aasm (5.5.0)
       concurrent-ruby (~> 1.0)
-    actioncable (7.1.3)
-      actionpack (= 7.1.3)
-      activesupport (= 7.1.3)
+    actioncable (7.1.3.2)
+      actionpack (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
       zeitwerk (~> 2.6)
-    actionmailbox (7.1.3)
-      actionpack (= 7.1.3)
-      activejob (= 7.1.3)
-      activerecord (= 7.1.3)
-      activestorage (= 7.1.3)
-      activesupport (= 7.1.3)
+    actionmailbox (7.1.3.2)
+      actionpack (= 7.1.3.2)
+      activejob (= 7.1.3.2)
+      activerecord (= 7.1.3.2)
+      activestorage (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       mail (>= 2.7.1)
       net-imap
       net-pop
       net-smtp
-    actionmailer (7.1.3)
-      actionpack (= 7.1.3)
-      actionview (= 7.1.3)
-      activejob (= 7.1.3)
-      activesupport (= 7.1.3)
+    actionmailer (7.1.3.2)
+      actionpack (= 7.1.3.2)
+      actionview (= 7.1.3.2)
+      activejob (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       mail (~> 2.5, >= 2.5.4)
       net-imap
       net-pop
       net-smtp
       rails-dom-testing (~> 2.2)
-    actionpack (7.1.3)
-      actionview (= 7.1.3)
-      activesupport (= 7.1.3)
+    actionpack (7.1.3.2)
+      actionview (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       nokogiri (>= 1.8.5)
       racc
       rack (>= 2.2.4)
@@ -66,27 +66,27 @@ GEM
       rack-test (>= 0.6.3)
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
-    actiontext (7.1.3)
-      actionpack (= 7.1.3)
-      activerecord (= 7.1.3)
-      activestorage (= 7.1.3)
-      activesupport (= 7.1.3)
+    actiontext (7.1.3.2)
+      actionpack (= 7.1.3.2)
+      activerecord (= 7.1.3.2)
+      activestorage (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       globalid (>= 0.6.0)
       nokogiri (>= 1.8.5)
-    actionview (7.1.3)
-      activesupport (= 7.1.3)
+    actionview (7.1.3.2)
+      activesupport (= 7.1.3.2)
       builder (~> 3.1)
       erubi (~> 1.11)
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
-    activejob (7.1.3)
-      activesupport (= 7.1.3)
+    activejob (7.1.3.2)
+      activesupport (= 7.1.3.2)
       globalid (>= 0.3.6)
-    activemodel (7.1.3)
-      activesupport (= 7.1.3)
-    activerecord (7.1.3)
-      activemodel (= 7.1.3)
-      activesupport (= 7.1.3)
+    activemodel (7.1.3.2)
+      activesupport (= 7.1.3.2)
+    activerecord (7.1.3.2)
+      activemodel (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       timeout (>= 0.4.0)
     activerecord-session_store (2.1.0)
       actionpack (>= 6.1)
@@ -95,13 +95,13 @@ GEM
       multi_json (~> 1.11, >= 1.11.2)
       rack (>= 2.0.8, < 4)
       railties (>= 6.1)
-    activestorage (7.1.3)
-      actionpack (= 7.1.3)
-      activejob (= 7.1.3)
-      activerecord (= 7.1.3)
-      activesupport (= 7.1.3)
+    activestorage (7.1.3.2)
+      actionpack (= 7.1.3.2)
+      activejob (= 7.1.3.2)
+      activerecord (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       marcel (~> 1.0)
-    activesupport (7.1.3)
+    activesupport (7.1.3.2)
       base64
       bigdecimal
       concurrent-ruby (~> 1.0, >= 1.0.2)
@@ -204,8 +204,7 @@ GEM
     dotenv-rails (2.8.1)
       dotenv (= 2.8.1)
       railties (>= 3.2)
-    drb (2.2.0)
-      ruby2_keywords
+    drb (2.2.1)
     erubi (1.12.0)
     execjs (2.8.1)
     factory_bot (6.4.5)
@@ -249,11 +248,12 @@ GEM
     http-accept (1.7.0)
     http-cookie (1.0.5)
       domain_name (~> 0.5)
-    i18n (1.14.1)
+    i18n (1.14.3)
       concurrent-ruby (~> 1.0)
+      racc (~> 1.7)
     io-console (0.7.2)
     io-event (1.2.2)
-    irb (1.11.1)
+    irb (1.11.2)
       rdoc
       reline (>= 0.4.2)
     jquery-rails (4.6.0)
@@ -271,7 +271,7 @@ GEM
       net-imap
       net-pop
       net-smtp
-    marcel (1.0.2)
+    marcel (1.0.4)
     matrix (0.4.2)
     mime-types (3.5.2)
       mime-types-data (~> 3.2015)
@@ -324,7 +324,7 @@ GEM
       stringio
     public_suffix (5.0.4)
     racc (1.7.3)
-    rack (2.2.8)
+    rack (2.2.8.1)
     rack-session (1.0.2)
       rack (< 3)
     rack-test (2.1.0)
@@ -332,20 +332,20 @@ GEM
     rackup (1.0.0)
       rack (< 3)
       webrick
-    rails (7.1.3)
-      actioncable (= 7.1.3)
-      actionmailbox (= 7.1.3)
-      actionmailer (= 7.1.3)
-      actionpack (= 7.1.3)
-      actiontext (= 7.1.3)
-      actionview (= 7.1.3)
-      activejob (= 7.1.3)
-      activemodel (= 7.1.3)
-      activerecord (= 7.1.3)
-      activestorage (= 7.1.3)
-      activesupport (= 7.1.3)
+    rails (7.1.3.2)
+      actioncable (= 7.1.3.2)
+      actionmailbox (= 7.1.3.2)
+      actionmailer (= 7.1.3.2)
+      actionpack (= 7.1.3.2)
+      actiontext (= 7.1.3.2)
+      actionview (= 7.1.3.2)
+      activejob (= 7.1.3.2)
+      activemodel (= 7.1.3.2)
+      activerecord (= 7.1.3.2)
+      activestorage (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       bundler (>= 1.15.0)
-      railties (= 7.1.3)
+      railties (= 7.1.3.2)
     rails-controller-testing (1.0.5)
       actionpack (>= 5.0.1.rc1)
       actionview (>= 5.0.1.rc1)
@@ -357,9 +357,9 @@ GEM
     rails-html-sanitizer (1.6.0)
       loofah (~> 2.21)
       nokogiri (~> 1.14)
-    railties (7.1.3)
-      actionpack (= 7.1.3)
-      activesupport (= 7.1.3)
+    railties (7.1.3.2)
+      actionpack (= 7.1.3.2)
+      activesupport (= 7.1.3.2)
       irb
       rackup (>= 1.0.0)
       rake (>= 12.2)
@@ -374,7 +374,7 @@ GEM
     rdoc (6.6.2)
       psych (>= 4.0.0)
     regexp_parser (2.9.0)
-    reline (0.4.2)
+    reline (0.4.3)
       io-console (~> 0.5)
     rest-client (2.1.0)
       http-accept (>= 1.7.0, < 2.0)
@@ -469,7 +469,7 @@ GEM
     stringio (3.1.0)
     sucker_punch (3.2.0)
       concurrent-ruby (~> 1.0)
-    thor (1.3.0)
+    thor (1.3.1)
     tilt (2.2.0)
     timeout (0.4.1)
     timers (4.3.5)
@@ -492,7 +492,7 @@ GEM
     websocket-extensions (0.1.5)
     xpath (3.2.0)
       nokogiri (~> 1.8)
-    zeitwerk (2.6.12)
+    zeitwerk (2.6.13)
 
 PLATFORMS
   ruby
diff --git a/app/controllers/flood_risk_engine/application_controller.rb b/app/controllers/flood_risk_engine/application_controller.rb
index cf25f15b..7dc0ef48 100644
--- a/app/controllers/flood_risk_engine/application_controller.rb
+++ b/app/controllers/flood_risk_engine/application_controller.rb
@@ -6,6 +6,12 @@ class ApplicationController < ActionController::Base
 
     layout ->(_) { FloodRiskEngine.config.layout }
 
+    rescue_from StandardError do |e|
+      Airbrake.notify e
+      Rails.logger.error "Unhandled exception: #{e}\n#{e.backtrace}"
+      redirect_to error_path("500")
+    end
+
     protected
 
     # http://jacopretorius.net/2014/01/force-page-to-reload-on-browser-back-in-rails.html
diff --git a/app/controllers/flood_risk_engine/errors_controller.rb b/app/controllers/flood_risk_engine/errors_controller.rb
index 664d8efe..e2a3ea33 100644
--- a/app/controllers/flood_risk_engine/errors_controller.rb
+++ b/app/controllers/flood_risk_engine/errors_controller.rb
@@ -5,15 +5,27 @@
 module FloodRiskEngine
   class ErrorsController < ApplicationController
 
+    before_action :set_html_response_format
+
     def show
       render(
         template: file_for(template),
-        locals: { message: exception.try(:message), enrollment: }
+        locals: { message: exception.try(:message), enrollment: },
+        status: response_status
       )
     end
 
     protected
 
+    # Changes the request format to HTML to always display the error pages
+    def set_html_response_format
+      request.format = :html
+    end
+
+    def response_status
+      template.to_i.positive? ? template : :internal_server_error
+    end
+
     def error_code
       @error_code ||= params[:id]
     end
@@ -30,7 +42,11 @@ def template_path(name)
     end
 
     def template
-      @template ||= template_exists(error_code) ? error_code : "generic"
+      @template ||= if template_exists(error_code)
+                      error_code
+                    else
+                      (error_code.to_i.positive? ? "generic" : "404")
+                    end
     end
 
     def file_for(name)
diff --git a/config/locales/flood_risk_engine/errors.en.yml b/config/locales/flood_risk_engine/errors.en.yml
index 834190ab..1e02129c 100644
--- a/config/locales/flood_risk_engine/errors.en.yml
+++ b/config/locales/flood_risk_engine/errors.en.yml
@@ -17,12 +17,12 @@ en:
         heading: Page not found
         if_you_typed: If you typed the web address, check it is correct.
         if_you_pasted: If you pasted the web address, check you copied the entire address.
-        call_our_helpline: If the web address is correct or you selected a link or button, call our helpline on 03708 506 506,
+        call_our_helpline: If the web address is correct or you selected a link or button, call our helpline on 03708 506 506.
       error_404:
         heading: Page not found
         if_you_typed: If you typed the web address, check it is correct.
         if_you_pasted: If you pasted the web address, check you copied the entire address.
-        call_our_helpline: If the web address is correct or you selected a link or button, call our helpline on 03708 506 506,
+        call_our_helpline: If the web address is correct or you selected a link or button, call our helpline on 03708 506 506.
       error_422:
         heading: There was a problem
         sorry: Sorry, the system wasn't able to complete that step.
diff --git a/config/routes.rb b/config/routes.rb
index 1856a37a..3f80c90e 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -242,7 +242,7 @@
 
   mount DefraRubyEmail::Engine => "/email"
 
-  # See http://patrickperey.com/railscast-053-handling-exceptions/
+  # See http://railscasts.com/episodes/53-handling-exceptions-revised
   get "(errors)/:id", to: "errors#show", as: "error"
 end
 # rubocop:enable Metrics/BlockLength
diff --git a/spec/controllers/flood_risk_engine/errors_controller_spec.rb b/spec/controllers/flood_risk_engine/errors_controller_spec.rb
deleted file mode 100644
index a6fdf420..00000000
--- a/spec/controllers/flood_risk_engine/errors_controller_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-# frozen_string_literal: true
-
-require "rails_helper"
-
-module FloodRiskEngine
-  RSpec.describe ErrorsController do
-    routes { Engine.routes }
-    render_views
-    describe "#show" do
-      it "renders error templates when known" do
-        get :show, params: { id: "401" }
-        expect(response).to have_http_status(:success)
-        expect(response).to render_template(:error_401)
-      end
-
-      it "renders generic when not known" do
-        get :show, params: { id: "unknown" }
-        expect(response).to have_http_status(:success)
-        expect(response).to render_template(:error_generic)
-      end
-    end
-  end
-end
diff --git a/spec/requests/flood_risk_engine/errors_spec.rb b/spec/requests/flood_risk_engine/errors_spec.rb
new file mode 100644
index 00000000..2f62722f
--- /dev/null
+++ b/spec/requests/flood_risk_engine/errors_spec.rb
@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+module FloodRiskEngine
+  RSpec.describe "Errors" do
+
+    before do
+      env_config = Rails.application.env_config
+      allow(env_config).to receive(:[]).with("action_dispatch.show_exceptions").and_return(true)
+      allow(env_config).to receive(:[]).with("action_dispatch.show_detailed_exceptions").and_return(false)
+    end
+
+    shared_examples "not found" do |path|
+      before { get path }
+
+      it "responds with HTTP 404" do
+        expect(response).to have_http_status(:not_found)
+      end
+
+      it "renders a HTML error page" do
+        expect(response.headers["Content-Type"]).to include("text/html")
+      end
+
+      it "includes expected error text" do
+        expect(response.body).to match(/If you typed the web address/)
+      end
+    end
+
+    describe "explicit error paths" do
+      context "when a matching error template exists" do
+        %w[401 403 404 422].each do |code|
+          it "responds with a status of #{code} and renders the error_#{code} template" do
+            get error_path(code)
+
+            expect(response.code).to eq(code)
+            expect(response).to render_template("error_#{code}")
+          end
+        end
+      end
+
+      context "when no matching error template exists" do
+        it "renders the generic error template" do
+          get error_path("601")
+
+          expect(response).to have_http_status(:internal_server_error)
+          expect(response).to render_template(:error_generic)
+        end
+      end
+    end
+
+    describe "internal redirects to error pages" do
+      context "when the requested route does not exist" do
+        context "when the requested route format is not specified" do
+          it_behaves_like "not found", "/this-page-does-not-exist"
+        end
+
+        context "when the requested route format is html" do
+          it_behaves_like "not found", "/this-page-does-not-exist.html"
+        end
+
+        context "when the requested route format is not html" do
+          it_behaves_like "not found", "/this-page-does-not-exist.xml"
+        end
+      end
+    end
+
+    context "when an unhandled internal system error occurs (500)" do
+
+      let(:start_forms_controller) { FloodRiskEngine::StartFormsController.new }
+
+      before do
+        allow(FloodRiskEngine::StartFormsController).to receive(:new).and_return(start_forms_controller)
+        allow(start_forms_controller).to receive(:create).and_raise(StandardError)
+      end
+
+      it do
+        post start_forms_path
+
+        expect(response).to redirect_to error_path("500")
+      end
+    end
+  end
+end