diff --git a/assets/app.js b/assets/app.js
index 3cb7ffc..96924db 100644
--- a/assets/app.js
+++ b/assets/app.js
@@ -23,3 +23,11 @@ htmx.config.responseHandling = [
     { code: '422', swap: true, error: false },
     { code: '[45]..', swap: false, error: true },
 ];
+
+// Anything else that fails -- a 4xx other than 422, a 5xx, or no response at all -- reloads the
+// page. htmx only opens modals and refreshes fragments, so there is always a whole page underneath,
+// and every page is a GET: reloading is safe, closes the modal and shows current data. The server
+// keeps honest status codes and leaves a flash explaining the reload (HtmxErrorFlashListener).
+const reloadPage = () => window.location.reload();
+document.addEventListener('htmx:responseError', reloadPage);
+document.addEventListener('htmx:sendError', reloadPage);
diff --git a/config/packages/security.yaml b/config/packages/security.yaml
index 80203e5..a81bf21 100644
--- a/config/packages/security.yaml
+++ b/config/packages/security.yaml
@@ -10,7 +10,8 @@ security:
 
     firewalls:
         dev:
-            pattern: ^/(_profiler|_wdt|assets)/
+            # _error is the dev-only preview of the error pages (/_error/404, /_error/500).
+            pattern: ^/(_profiler|_wdt|_error|assets)/
             security: false
         main:
             lazy: true
diff --git a/src/EventListener/HtmxErrorFlashListener.php b/src/EventListener/HtmxErrorFlashListener.php
new file mode 100644
index 0000000..1dc1c41
--- /dev/null
+++ b/src/EventListener/HtmxErrorFlashListener.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\EventListener;
+
+use Symfony\Component\EventDispatcher\Attribute\AsEventListener;
+use Symfony\Component\HttpFoundation\Session\FlashBagAwareSessionInterface;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\KernelEvents;
+
+/**
+ * Leaves a flash behind when an htmx request fails, for the page reload that follows.
+ *
+ * htmx is only used for modals and out-of-band refreshes, so there is always a whole page under a
+ * failed request -- and every page is a GET. assets/app.js therefore answers a failed htmx request
+ * by reloading that page, and this flash is what tells the user why it just reloaded.
+ *
+ * It only adds the flash. The response is left alone, so it keeps its real status and Symfony
+ * logs the exception as usual. A listener that already produced a response stops propagation
+ * before this runs -- notably the firewall's entry point, which sends an expired session to the
+ * login page with HX-Redirect instead.
+ */
+#[AsEventListener(event: KernelEvents::EXCEPTION, priority: -10)]
+final class HtmxErrorFlashListener
+{
+    public function __invoke(ExceptionEvent $event): void
+    {
+        $request = $event->getRequest();
+
+        if (!$request->headers->has('HX-Request') || !$request->hasSession()) {
+            return;
+        }
+
+        $session = $request->getSession();
+
+        if ($session instanceof FlashBagAwareSessionInterface) {
+            $session->getFlashBag()->add('error', 'Da ist etwas schiefgelaufen. Bitte versuche es erneut.');
+        }
+    }
+}
diff --git a/src/EventListener/HtmxExceptionListener.php b/src/EventListener/HtmxExceptionListener.php
deleted file mode 100644
index d42a03e..0000000
--- a/src/EventListener/HtmxExceptionListener.php
+++ /dev/null
@@ -1,48 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\EventListener;
-
-use Symfony\Component\EventDispatcher\Attribute\AsEventListener;
-use Symfony\Component\HttpFoundation\Response;
-use Symfony\Component\HttpKernel\Event\ExceptionEvent;
-use Symfony\Component\HttpKernel\KernelEvents;
-use Twig\Environment;
-
-/**
- * Renders an error modal when an htmx request blows up.
- *
- * htmx does not swap a 5xx by default, so an uncaught exception on a fragment request produces
- * no visible effect whatsoever -- the user clicks and nothing happens. This turns it into
- * something they can see: a 200 carrying the error modal, retargeted at <body> so it appends
- * regardless of what the original hx-target was.
- *
- * allowCustomResponseCode() is what keeps the 200; without it the kernel rewrites it to 500 and
- * htmx discards the body again.
- */
-#[AsEventListener(event: KernelEvents::EXCEPTION, priority: -10)]
-final readonly class HtmxExceptionListener
-{
-    public function __construct(private Environment $twig)
-    {
-    }
-
-    public function __invoke(ExceptionEvent $event): void
-    {
-        if (!$event->getRequest()->headers->has('HX-Request')) {
-            return;
-        }
-
-        if ($event->hasResponse()) {
-            return;
-        }
-
-        $response = new Response($this->twig->render('htmx_error_modal.html.twig'), Response::HTTP_OK);
-        $response->headers->set('HX-Retarget', 'body');
-        $response->headers->set('HX-Reswap', 'beforeend');
-
-        $event->setResponse($response);
-        $event->allowCustomResponseCode();
-    }
-}
diff --git a/src/Security/LoginEntryPoint.php b/src/Security/LoginEntryPoint.php
index 050e9e5..b7f34c6 100644
--- a/src/Security/LoginEntryPoint.php
+++ b/src/Security/LoginEntryPoint.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Security;
 
+use App\Htmx\HxRedirectResponse;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
@@ -16,6 +17,10 @@ use Symfony\Component\Security\Http\EntryPoint\AuthenticationEntryPointInterface
  *
  * Deliberately the login *page* rather than straight into /auth/init: the page is where a failed
  * login's flash message is shown, and bouncing there instead would swallow it.
+ *
+ * An htmx request -- typically a click after the session expired -- gets HX-Redirect instead:
+ * a plain 302 is followed invisibly by the browser, and htmx would swap the whole login page into
+ * whatever the click targeted, a modal included.
  */
 final readonly class LoginEntryPoint implements AuthenticationEntryPointInterface
 {
@@ -25,6 +30,12 @@ final readonly class LoginEntryPoint implements AuthenticationEntryPointInterfac
 
     public function start(Request $request, ?AuthenticationException $authException = null): Response
     {
-        return new RedirectResponse($this->urlGenerator->generate('app_login'));
+        $url = $this->urlGenerator->generate('app_login');
+
+        if ($request->headers->has('HX-Request')) {
+            return new HxRedirectResponse($url);
+        }
+
+        return new RedirectResponse($url);
     }
 }
diff --git a/templates/bundles/TwigBundle/Exception/error.html.twig b/templates/bundles/TwigBundle/Exception/error.html.twig
new file mode 100644
index 0000000..49219f3
--- /dev/null
+++ b/templates/bundles/TwigBundle/Exception/error.html.twig
@@ -0,0 +1,21 @@
+{#
+    Symfony's error page for anything but a 404, adopted from myep-team. Only used with debug off;
+    dev keeps showing the exception page (preview at /_error/500).
+
+    Never reached by an htmx request: a failed one reloads its page instead (see assets/app.js).
+#}
+{% extends 'layout.html.twig' %}
+
+{% block title %}Fehler · ephub{% endblock %}
+
+{% block content %}
+    <h1 class="text-2xl font-bold pb-8">
+        Oops... Ein Fehler ist aufgetreten
+    </h1>
+    <p class="mb-8">
+        Wir haben uns ein paar Notizen dazu gemacht und werden das Problem so schnell wie möglich beseitigen.
+    </p>
+    <a class="button button--primary" href="{{ path('app_dashboard') }}">
+        nochmal von vorne
+    </a>
+{% endblock %}
diff --git a/templates/bundles/TwigBundle/Exception/error404.html.twig b/templates/bundles/TwigBundle/Exception/error404.html.twig
new file mode 100644
index 0000000..ac262f4
--- /dev/null
+++ b/templates/bundles/TwigBundle/Exception/error404.html.twig
@@ -0,0 +1,16 @@
+{# Symfony's 404 page, adopted from myep-team. Only used with debug off. #}
+{% extends 'layout.html.twig' %}
+
+{% block title %}Nicht gefunden · ephub{% endblock %}
+
+{% block content %}
+    <h1 class="text-2xl font-bold pb-8">
+        Oops... Ein Fehler ist aufgetreten
+    </h1>
+    <p class="mb-8">
+        Die von dir aufgerufene Seite können wir leider nicht (mehr) finden.
+    </p>
+    <a class="button button--primary" href="{{ path('app_dashboard') }}">
+        nochmal von vorne
+    </a>
+{% endblock %}
diff --git a/templates/htmx_error_modal.html.twig b/templates/htmx_error_modal.html.twig
deleted file mode 100644
index c5c959d..0000000
--- a/templates/htmx_error_modal.html.twig
+++ /dev/null
@@ -1,9 +0,0 @@
-{% embed 'htmx_modal.html.twig' %}
-    {% block title %}Oops…{% endblock %}
-    {% block content %}
-        <div class="bg-red-600 text-gray-100 rounded px-4 py-3 text-sm">
-            Da ist etwas schiefgelaufen. Wir haben uns Notizen gemacht und kümmern uns
-            schnellstmöglich darum.
-        </div>
-    {% endblock %}
-{% endembed %}
diff --git a/tests/Controller/Admin/ResourceAdminControllerTest.php b/tests/Controller/Admin/ResourceAdminControllerTest.php
index c23e6c8..30f6cc8 100644
--- a/tests/Controller/Admin/ResourceAdminControllerTest.php
+++ b/tests/Controller/Admin/ResourceAdminControllerTest.php
@@ -43,8 +43,7 @@ class ResourceAdminControllerTest extends WebTestCase
         $this->client->request('GET', '/admin/resources');
         self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
 
-        // Not as htmx: an htmx request gets the error modal instead of the bare status.
-        $this->client->request('GET', '/admin/resources/new/desk');
+        $this->client->request('GET', '/admin/resources/new/desk', server: ['HTTP_HX-Request' => 'true']);
         self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
     }
 
@@ -123,7 +122,7 @@ class ResourceAdminControllerTest extends WebTestCase
     {
         $this->client->loginUser($this->admin());
 
-        $this->client->request('GET', '/admin/resources/new/boat');
+        $this->client->request('GET', '/admin/resources/new/boat', server: ['HTTP_HX-Request' => 'true']);
 
         self::assertResponseStatusCodeSame(Response::HTTP_NOT_FOUND);
     }
@@ -221,7 +220,7 @@ class ResourceAdminControllerTest extends WebTestCase
         $crawler = $this->client->request('GET', '/admin/resources');
         self::assertCount(0, $crawler->filter(\sprintf('[hx-get="/admin/resource-groups/%d/delete"]', $room->getId())));
 
-        $this->client->request('POST', \sprintf('/admin/resource-groups/%d/delete', $room->getId()), ['_token' => 'whatever']);
+        $this->client->request('POST', \sprintf('/admin/resource-groups/%d/delete', $room->getId()), ['_token' => 'whatever'], server: ['HTTP_HX-Request' => 'true']);
         self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
     }
 
diff --git a/tests/Controller/BookingControllerTest.php b/tests/Controller/BookingControllerTest.php
index e042cb4..289cb1e 100644
--- a/tests/Controller/BookingControllerTest.php
+++ b/tests/Controller/BookingControllerTest.php
@@ -155,12 +155,6 @@ class BookingControllerTest extends WebTestCase
         self::assertNull($this->em->getRepository(Booking::class)->findOneBy(['resource' => $desk]));
     }
 
-    /**
-     * Note the status is 200, not 403: HtmxExceptionListener deliberately converts every
-     * exception on an htmx request -- access denied included -- into a visible error modal,
-     * because htmx discards a 4xx body and the click would otherwise do nothing at all.
-     * What matters here is that the booking survives.
-     */
     public function testReleasingAnotherPersonsBookingIsRefused(): void
     {
         $booking = new Booking($this->user('bea@ep-reisen.de'), $this->resource('D1'), new \DateTimeImmutable('2026-10-01'));
@@ -170,8 +164,7 @@ class BookingControllerTest extends WebTestCase
         $this->client->loginUser($this->user('anna@ep-reisen.de'));
         $this->client->request('POST', \sprintf('/bookings/%d/release', $booking->getId()), server: ['HTTP_HX-Request' => 'true']);
 
-        $response = $this->client->getResponse();
-        self::assertSame('body', $response->headers->get('HX-Retarget'));
+        self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
         self::assertNotNull($this->em->getRepository(Booking::class)->find($booking->getId()));
     }
 
diff --git a/tests/EventListener/HtmxErrorFlashListenerTest.php b/tests/EventListener/HtmxErrorFlashListenerTest.php
new file mode 100644
index 0000000..6c89e19
--- /dev/null
+++ b/tests/EventListener/HtmxErrorFlashListenerTest.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\EventListener;
+
+use App\Entity\User;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bundle\FrameworkBundle\KernelBrowser;
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * A failed htmx request keeps its status, and the page reload that app.js answers it with shows
+ * why it happened.
+ */
+class HtmxErrorFlashListenerTest extends WebTestCase
+{
+    private const MESSAGE = 'Da ist etwas schiefgelaufen.';
+
+    private KernelBrowser $client;
+    private EntityManagerInterface $em;
+
+    protected function setUp(): void
+    {
+        $this->client = self::createClient();
+        $this->client->disableReboot();
+        $this->em = self::getContainer()->get(EntityManagerInterface::class);
+        $this->em->getConnection()->beginTransaction();
+
+        $user = new User('anna@ep-reisen.de', 'Anna');
+        $user->setRoles(['ROLE_EMPLOYEE']);
+        $this->em->persist($user);
+        $this->em->flush();
+        $this->client->loginUser($user);
+    }
+
+    protected function tearDown(): void
+    {
+        $this->em->getConnection()->rollBack();
+        parent::tearDown();
+    }
+
+    public function testAFailedHtmxRequestKeepsItsStatusAndLeavesAFlash(): void
+    {
+        $this->client->request('GET', '/admin/resources', server: ['HTTP_HX-Request' => 'true']);
+        self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
+        self::assertFalse($this->client->getResponse()->headers->has('HX-Retarget'));
+
+        $this->client->request('GET', '/');
+        self::assertSelectorTextContains('#flashes', self::MESSAGE);
+    }
+
+    /**
+     * An ordinary page request shows Symfony's error page instead, so a flash would only turn up
+     * later, out of context.
+     */
+    public function testAnOrdinaryRequestLeavesNoFlash(): void
+    {
+        $this->client->request('GET', '/admin/resources');
+        self::assertResponseStatusCodeSame(Response::HTTP_FORBIDDEN);
+
+        $this->client->request('GET', '/');
+        self::assertSelectorTextNotContains('#flashes', self::MESSAGE);
+    }
+}
diff --git a/tests/EventListener/HtmxExceptionListenerFunctionalTest.php b/tests/EventListener/HtmxExceptionListenerFunctionalTest.php
deleted file mode 100644
index 40ade03..0000000
--- a/tests/EventListener/HtmxExceptionListenerFunctionalTest.php
+++ /dev/null
@@ -1,45 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\Tests\EventListener;
-
-use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
-use Symfony\Component\HttpFoundation\Response;
-
-/**
- * Drives the listener through the real kernel, which is the only way to prove
- * allowCustomResponseCode() actually holds the 200 -- the kernel rewrites it otherwise, and a
- * unit test on the event object cannot see that happen.
- *
- * An unrouted path is used as the exception source so no throwing fixture controller is needed.
- */
-class HtmxExceptionListenerFunctionalTest extends WebTestCase
-{
-    public function testAnExceptionOnAnHtmxRequestArrivesAsA200ErrorModal(): void
-    {
-        $client = self::createClient();
-        $client->catchExceptions(true);
-        $client->request('GET', '/does-not-exist', server: ['HTTP_HX-Request' => 'true']);
-
-        $response = $client->getResponse();
-        self::assertSame(Response::HTTP_OK, $response->getStatusCode());
-        self::assertSame('body', $response->headers->get('HX-Retarget'));
-        self::assertSame('beforeend', $response->headers->get('HX-Reswap'));
-        self::assertStringContainsString('id="htmx-modal"', (string) $response->getContent());
-    }
-
-    public function testTheSameExceptionOnAnOrdinaryRequestStillGivesAnHonestErrorStatus(): void
-    {
-        $client = self::createClient();
-        $client->catchExceptions(true);
-        $client->request('GET', '/does-not-exist');
-
-        // Asserting on headers rather than body: in debug mode Symfony's exception page renders
-        // the source of every stack frame, this file included, so any marker string searched for
-        // here would match its own source code.
-        self::assertSame(Response::HTTP_NOT_FOUND, $client->getResponse()->getStatusCode());
-        self::assertFalse($client->getResponse()->headers->has('HX-Retarget'));
-        self::assertFalse($client->getResponse()->headers->has('HX-Reswap'));
-    }
-}
diff --git a/tests/EventListener/HtmxExceptionListenerTest.php b/tests/EventListener/HtmxExceptionListenerTest.php
deleted file mode 100644
index 6e135cd..0000000
--- a/tests/EventListener/HtmxExceptionListenerTest.php
+++ /dev/null
@@ -1,94 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\Tests\EventListener;
-
-use App\EventListener\HtmxExceptionListener;
-use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
-use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpFoundation\Response;
-use Symfony\Component\HttpKernel\Event\ExceptionEvent;
-use Symfony\Component\HttpKernel\HttpKernelInterface;
-use Twig\Environment;
-
-/**
- * Uses the real Twig so the error modal template is exercised too -- an unrenderable modal here
- * would throw from inside exception handling, which is the worst possible place for it.
- */
-class HtmxExceptionListenerTest extends KernelTestCase
-{
-    public function testHtmxRequestsGetTheErrorModalAsA200(): void
-    {
-        $event = $this->dispatch(['HTTP_HX-Request' => 'true']);
-
-        $response = $event->getResponse();
-        self::assertInstanceOf(Response::class, $response);
-        // 200, not 500: htmx does not swap 5xx, so an error response would be discarded unseen.
-        self::assertSame(Response::HTTP_OK, $response->getStatusCode());
-        // Without this the kernel turns the 200 back into a 500.
-        self::assertTrue($event->isAllowingCustomResponseCode());
-    }
-
-    public function testTheModalIsRetargetedAtTheBodySoItAppearsWhateverTheTriggerWas(): void
-    {
-        $response = $this->dispatch(['HTTP_HX-Request' => 'true'])->getResponse();
-
-        self::assertNotNull($response);
-        self::assertSame('body', $response->headers->get('HX-Retarget'));
-        self::assertSame('beforeend', $response->headers->get('HX-Reswap'));
-    }
-
-    public function testTheRenderedModalIsTheStandaloneModalFragment(): void
-    {
-        $content = (string) $this->dispatch(['HTTP_HX-Request' => 'true'])->getResponse()?->getContent();
-
-        self::assertStringContainsString('id="htmx-modal"', $content);
-        self::assertStringContainsString('data-controller="modal"', $content);
-        self::assertStringNotContainsString('<html', $content);
-    }
-
-    public function testOrdinaryRequestsAreLeftToSymfonysErrorHandling(): void
-    {
-        self::assertNull($this->dispatch()->getResponse());
-    }
-
-    public function testAResponseSetByAnEarlierListenerIsNotOverwritten(): void
-    {
-        $event = $this->event(['HTTP_HX-Request' => 'true']);
-        $event->setResponse($alreadySet = new Response('handled elsewhere'));
-
-        ($this->listener())($event);
-
-        self::assertSame($alreadySet, $event->getResponse());
-    }
-
-    /**
-     * @param array<string, string> $server
-     */
-    private function dispatch(array $server = []): ExceptionEvent
-    {
-        $event = $this->event($server);
-        ($this->listener())($event);
-
-        return $event;
-    }
-
-    /**
-     * @param array<string, string> $server
-     */
-    private function event(array $server): ExceptionEvent
-    {
-        return new ExceptionEvent(
-            self::bootKernel(),
-            Request::create('/bookings', server: $server),
-            HttpKernelInterface::MAIN_REQUEST,
-            new \RuntimeException('boom'),
-        );
-    }
-
-    private function listener(): HtmxExceptionListener
-    {
-        return new HtmxExceptionListener(self::getContainer()->get(Environment::class));
-    }
-}
diff --git a/tests/Security/LoginEntryPointTest.php b/tests/Security/LoginEntryPointTest.php
new file mode 100644
index 0000000..18e63ac
--- /dev/null
+++ b/tests/Security/LoginEntryPointTest.php
@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Security;
+
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+
+class LoginEntryPointTest extends WebTestCase
+{
+    /**
+     * A plain 302 would be followed invisibly and the login page swapped into the click's target.
+     *
+     * The status stays 403 -- Symfony's firewall keeps the access-denied status on this path --
+     * and that is fine: htmx 2.0.10 acts on HX-Redirect before it looks at the status at all
+     * (handleAjaxResponse), so it navigates rather than raising htmx:responseError.
+     */
+    public function testAnExpiredSessionOnAnHtmxRequestNavigatesToTheLoginPage(): void
+    {
+        $client = self::createClient();
+
+        $client->request('GET', '/book/desk', server: ['HTTP_HX-Request' => 'true']);
+
+        self::assertSame('/login', $client->getResponse()->headers->get('HX-Redirect'));
+    }
+
+    public function testAnExpiredSessionOnAnOrdinaryRequestStillRedirects(): void
+    {
+        $client = self::createClient();
+
+        $client->request('GET', '/book/desk');
+
+        self::assertResponseRedirects('/login');
+    }
+}