diff --git a/passbook/core/templates/error/400.html b/passbook/core/templates/error/400.html
index 5cdbb3846..410263962 100644
--- a/passbook/core/templates/error/400.html
+++ b/passbook/core/templates/error/400.html
@@ -20,7 +20,7 @@
 </header>
 <form>
     {% if message %}
-    <p>{% trans message %}</p>
+    <h3>{% trans message %}</h3>
     {% endif %}
     {% if 'back' in request.GET %}
     <a href="{% back %}" class="btn btn-primary btn-block btn-lg">{% trans 'Back' %}</a>
diff --git a/passbook/factors/tests.py b/passbook/factors/tests.py
index 3622321e9..3311081a3 100644
--- a/passbook/factors/tests.py
+++ b/passbook/factors/tests.py
@@ -38,9 +38,8 @@ class TestFactorAuthentication(TestCase):
     def test_unauthenticated_raw(self):
         """test direct call to AuthenticationView"""
         response = self.client.get(reverse("passbook_core:auth-process"))
-        # Response should be 302 since no pending user is set
-        self.assertEqual(response.status_code, 302)
-        self.assertEqual(response.url, reverse("passbook_core:auth-login"))
+        # Response should be 400 since no pending user is set
+        self.assertEqual(response.status_code, 400)
 
     def test_unauthenticated_prepared(self):
         """test direct call but with pending_uesr in session"""
@@ -71,9 +70,8 @@ class TestFactorAuthentication(TestCase):
         """Test with already logged in user"""
         self.client.force_login(self.user)
         response = self.client.get(reverse("passbook_core:auth-process"))
-        # Response should be 302 since no pending user is set
-        self.assertEqual(response.status_code, 302)
-        self.assertEqual(response.url, reverse("passbook_core:overview"))
+        # Response should be 400 since no pending user is set
+        self.assertEqual(response.status_code, 400)
         self.client.logout()
 
     def test_unauthenticated_post(self):
diff --git a/passbook/factors/view.py b/passbook/factors/view.py
index b3546c216..e3702a5a0 100644
--- a/passbook/factors/view.py
+++ b/passbook/factors/view.py
@@ -1,15 +1,17 @@
 """passbook multi-factor authentication engine"""
-from typing import List, Tuple
+from typing import List, Optional, Tuple
 
 from django.contrib.auth import login
 from django.contrib.auth.mixins import UserPassesTestMixin
-from django.shortcuts import get_object_or_404, redirect, reverse
+from django.http import HttpRequest, HttpResponse
+from django.shortcuts import get_object_or_404, redirect, render, reverse
 from django.utils.http import urlencode
 from django.views.generic import View
 from structlog import get_logger
 
 from passbook.core.models import Factor, User
 from passbook.core.views.utils import PermissionDeniedView
+from passbook.lib.config import CONFIG
 from passbook.lib.utils.reflection import class_to_path, path_to_class
 from passbook.lib.utils.urls import is_url_absolute
 from passbook.policies.engine import PolicyEngine
@@ -44,10 +46,26 @@ class AuthenticationView(UserPassesTestMixin, View):
     current_factor: Factor
 
     # Allow only not authenticated users to login
-    def test_func(self):
+    def test_func(self) -> bool:
         return AuthenticationView.SESSION_PENDING_USER in self.request.session
 
-    def handle_no_permission(self):
+    def _check_config_domain(self) -> Optional[HttpResponse]:
+        """Checks if current request's domain matches configured Domain, and
+        adds a warning if not."""
+        current_domain = self.request.get_host()
+        config_domain = CONFIG.y("domain")
+        if current_domain != config_domain:
+            message = (
+                f"Current domain of '{current_domain}' doesn't "
+                f"match configured domain of '{config_domain}'."
+            )
+            LOGGER.warning(message)
+            return render(
+                self.request, "error/400.html", context={"message": message}, status=400
+            )
+        return None
+
+    def handle_no_permission(self) -> HttpResponse:
         # Function from UserPassesTestMixin
         if NEXT_ARG_NAME in self.request.GET:
             return redirect(self.request.GET.get(NEXT_ARG_NAME))
@@ -55,7 +73,7 @@ class AuthenticationView(UserPassesTestMixin, View):
             return _redirect_with_qs("passbook_core:overview", self.request.GET)
         return _redirect_with_qs("passbook_core:auth-login", self.request.GET)
 
-    def get_pending_factors(self):
+    def get_pending_factors(self) -> List[Tuple[str, str]]:
         """Loading pending factors from Database or load from session variable"""
         # Write pending factors to session
         if AuthenticationView.SESSION_PENDING_FACTORS in self.request.session:
@@ -67,6 +85,7 @@ class AuthenticationView(UserPassesTestMixin, View):
         )
         pending_factors = []
         for factor in _all_factors:
+            factor: Factor
             LOGGER.debug(
                 "Checking if factor applies to user",
                 factor=factor,
@@ -81,10 +100,13 @@ class AuthenticationView(UserPassesTestMixin, View):
                 LOGGER.debug("Factor applies", factor=factor, user=self.pending_user)
         return pending_factors
 
-    def dispatch(self, request, *args, **kwargs):
+    def dispatch(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
         # Check if user passes test (i.e. SESSION_PENDING_USER is set)
         user_test_result = self.get_test_func()()
         if not user_test_result:
+            incorrect_domain_message = self._check_config_domain()
+            if incorrect_domain_message:
+                return incorrect_domain_message
             return self.handle_no_permission()
         # Extract pending user from session (only remember uid)
         self.pending_user = get_object_or_404(
@@ -117,7 +139,7 @@ class AuthenticationView(UserPassesTestMixin, View):
         self._current_factor_class.request = request
         return super().dispatch(request, *args, **kwargs)
 
-    def get(self, request, *args, **kwargs):
+    def get(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
         """pass get request to current factor"""
         LOGGER.debug(
             "Passing GET",
@@ -125,7 +147,7 @@ class AuthenticationView(UserPassesTestMixin, View):
         )
         return self._current_factor_class.get(request, *args, **kwargs)
 
-    def post(self, request, *args, **kwargs):
+    def post(self, request: HttpRequest, *args, **kwargs) -> HttpResponse:
         """pass post request to current factor"""
         LOGGER.debug(
             "Passing POST",
@@ -133,7 +155,7 @@ class AuthenticationView(UserPassesTestMixin, View):
         )
         return self._current_factor_class.post(request, *args, **kwargs)
 
-    def user_ok(self):
+    def user_ok(self) -> HttpResponse:
         """Redirect to next Factor"""
         LOGGER.debug(
             "Factor passed",
@@ -160,14 +182,14 @@ class AuthenticationView(UserPassesTestMixin, View):
         LOGGER.debug("User passed all factors, logging in", user=self.pending_user)
         return self._user_passed()
 
-    def user_invalid(self):
+    def user_invalid(self) -> HttpResponse:
         """Show error message, user cannot login.
         This should only be shown if user authenticated successfully, but is disabled/locked/etc"""
         LOGGER.debug("User invalid")
         self.cleanup()
         return _redirect_with_qs("passbook_core:auth-denied", self.request.GET)
 
-    def _user_passed(self):
+    def _user_passed(self) -> HttpResponse:
         """User Successfully passed all factors"""
         backend = self.request.session[AuthenticationView.SESSION_USER_BACKEND]
         login(self.request, self.pending_user, backend=backend)