diff --git a/src/Controller/Booking/Create/IndexController.php b/src/Controller/Booking/Create/IndexController.php
index f62d596..fef1626 100644
--- a/src/Controller/Booking/Create/IndexController.php
+++ b/src/Controller/Booking/Create/IndexController.php
@@ -138,7 +138,8 @@ class IndexController extends AbstractController
                 return $this->redirectToRoute('app_account');
             }
 
-            return $this->redirect($returnUrl);
+            // Use htmxRedirect for cross-origin safety (returnUrl may be external)
+            return $this->htmxRedirect($request, $returnUrl);
         }
 
         return $this->render('booking/modal_cancel.html.twig');
diff --git a/src/Controller/Booking/Create/Step2Controller.php b/src/Controller/Booking/Create/Step2Controller.php
index e155796..b31c178 100644
--- a/src/Controller/Booking/Create/Step2Controller.php
+++ b/src/Controller/Booking/Create/Step2Controller.php
@@ -108,6 +108,7 @@ class Step2Controller extends AbstractController
             'bookingDto' => $bookingCreateDto,
             'cardsData' => $cardsData,
             'summaryData' => $summaryData,
+            'isSubmitted' => $form->isSubmitted(),
         ];
 
         return $this->render('booking/create/step_2.html.twig', $templateData);
@@ -123,7 +124,11 @@ class Step2Controller extends AbstractController
     )]
     public function editParticipant(int $index, Request $request): Response
     {
-        $bookingDto = $this->loadBookingDtoOrFail($request, BookingDto::MODE_CREATE);
+        $result = $this->loadBookingDtoOrRedirect($request, BookingDto::MODE_CREATE);
+        if ($result instanceof Response) {
+            return $result;
+        }
+        $bookingDto = $result;
 
         // Validate participant index
         if (false === isset($bookingDto->participants[$index])) {
@@ -178,7 +183,11 @@ class Step2Controller extends AbstractController
     )]
     public function refreshParticipantForm(int $index, Request $request): Response
     {
-        $bookingDto = $this->loadBookingDtoOrFail($request, BookingDto::MODE_CREATE);
+        $result = $this->loadBookingDtoOrRedirect($request, BookingDto::MODE_CREATE);
+        if ($result instanceof Response) {
+            return $result;
+        }
+        $bookingDto = $result;
 
         // Validate participant index
         if (false === isset($bookingDto->participants[$index])) {
diff --git a/src/Controller/Booking/Traits/BookingExceptionHandlerTrait.php b/src/Controller/Booking/Traits/BookingExceptionHandlerTrait.php
index 15f369b..40f3e0a 100644
--- a/src/Controller/Booking/Traits/BookingExceptionHandlerTrait.php
+++ b/src/Controller/Booking/Traits/BookingExceptionHandlerTrait.php
@@ -34,7 +34,7 @@ trait BookingExceptionHandlerTrait
         try {
             return $bookingService->getOrCreateBookingCreateDto($request);
         } catch (BookingSessionNotFoundException $e) {
-            $this->addFlash('error', 'Ihre Buchungssitzung ist abgelaufen. Bitte starten Sie eine neue Buchung.');
+            $this->addFlash('error', 'Deine Buchungssitzung ist abgelaufen. Bitte starte eine neue Buchung.');
 
             return $this->redirectToRoute('app_booking_create_error');
         } catch (TravelNotFoundException $e) {
diff --git a/src/Controller/Booking/Traits/ParticipantCardFlowTrait.php b/src/Controller/Booking/Traits/ParticipantCardFlowTrait.php
index 97b43be..403a1a5 100644
--- a/src/Controller/Booking/Traits/ParticipantCardFlowTrait.php
+++ b/src/Controller/Booking/Traits/ParticipantCardFlowTrait.php
@@ -8,6 +8,7 @@ use App\Form\BookingParticipantType;
 use App\Form\Model\BookingDto;
 use App\Form\Model\ParticipantEditDto;
 use Symfony\Component\Form\FormInterface;
+use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 
@@ -20,16 +21,18 @@ use Symfony\Component\HttpFoundation\Response;
 trait ParticipantCardFlowTrait
 {
     /**
-     * Load BookingDto from session or throw exception.
+     * Load BookingDto from session or return redirect to login.
      *
-     * @throws \RuntimeException When booking data not found in session
+     * Returns RedirectResponse when session data is missing (e.g., after cancel or session expiry).
      */
-    private function loadBookingDtoOrFail(Request $request, string $mode): BookingDto
+    private function loadBookingDtoOrRedirect(Request $request, string $mode): BookingDto|RedirectResponse
     {
         $bookingDto = $this->bookingService->getBookingDto($request, $mode);
 
         if (null === $bookingDto) {
-            throw new \RuntimeException(sprintf('Booking data not found in session for mode: %s', $mode));
+            $this->addFlash('info', 'Deine Sitzung ist abgelaufen. Bitte starte eine neue Buchung.');
+
+            return $this->redirectToRoute('app_login');
         }
 
         return $bookingDto;
@@ -183,4 +186,6 @@ trait ParticipantCardFlowTrait
     abstract private function render(string $view, array $parameters = [], ?Response $response = null): Response;
 
     abstract protected function addFlash(string $type, mixed $message): void;
+
+    abstract protected function redirectToRoute(string $route, array $parameters = [], int $status = 302): RedirectResponse;
 }
diff --git a/src/Htmx/HxTrait.php b/src/Htmx/HxTrait.php
index 0e3fcf5..616a372 100644
--- a/src/Htmx/HxTrait.php
+++ b/src/Htmx/HxTrait.php
@@ -4,10 +4,11 @@ declare(strict_types=1);
 
 namespace App\Htmx;
 
+use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 
 /**
- * Trait providing HTMX Out-of-Band swap functionality for controllers.
+ * Trait providing HTMX functionality for controllers.
  */
 trait HxTrait
 {
@@ -46,4 +47,23 @@ trait HxTrait
 
         return $response;
     }
+
+    /**
+     * Creates a redirect response that works correctly with HTMX requests.
+     *
+     * For HTMX requests, returns a 200 response with HX-Redirect header,
+     * which triggers a full page navigation (avoiding CORS issues with cross-origin redirects).
+     * For regular requests, returns a standard HTTP redirect.
+     */
+    protected function htmxRedirect(Request $request, string $url): Response
+    {
+        if ($request->headers->has('HX-Request')) {
+            $response = new Response('', Response::HTTP_OK);
+            $response->headers->set('HX-Redirect', $url);
+
+            return $response;
+        }
+
+        return $this->redirect($url);
+    }
 }
diff --git a/templates/booking/create/error.html.twig b/templates/booking/create/error.html.twig
index 7b5b9b4..540cf6a 100644
--- a/templates/booking/create/error.html.twig
+++ b/templates/booking/create/error.html.twig
@@ -12,7 +12,8 @@
             messages: errorMessages
         } %}
 
-        <a href="{{ returnUrl }}" class="button button--secondary">
+        {# hx-boost disabled for cross-origin #}
+        <a href="{{ returnUrl }}" hx-boost="false" class="button button--secondary">
             Zurück
         </a>
     </div>
diff --git a/templates/booking/create/success.html.twig b/templates/booking/create/success.html.twig
index 85f03a2..664d679 100644
--- a/templates/booking/create/success.html.twig
+++ b/templates/booking/create/success.html.twig
@@ -47,8 +47,8 @@
                     </li>
                 </ul>
             {% else %}
-                {# Guest user - show simple homepage link #}
-                <a href="{{ returnUrl }}" class="button button--primary">
+                {# Guest user - show simple homepage link (hx-boost disabled for cross-origin) #}
+                <a href="{{ returnUrl }}" hx-boost="false" class="button button--primary">
                     Zurück
                 </a>
             {% endif %}