diff --git a/src/Controller/FacetBlockAjaxController.php b/src/Controller/FacetBlockAjaxController.php
--- a/src/Controller/FacetBlockAjaxController.php	(revision 297bc08b8054da8d20b728bcca3f6f0028e1819e)
+++ b/src/Controller/FacetBlockAjaxController.php	(date 1723051123353)
@@ -13,6 +13,8 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpFoundation\Session\Session;
+use Symfony\Component\HttpFoundation\Session\Storage\MockArraySessionStorage;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Symfony\Component\Routing\RouterInterface;

@@ -132,10 +134,18 @@

     $new_request = Request::create($path);
     $request_stack = new RequestStack();
+    $session = new Session(new MockArraySessionStorage());
+    $session->start();
+    $new_request->setSession($session);
+

     $processed = $this->pathProcessor->processInbound($path, $new_request);
     $processed_request = Request::create($processed);

+    $session = new Session(new MockArraySessionStorage());
+    $session->start();
+    $processed_request->setSession($session);
+
     $this->currentPath->setPath($processed_request->getPathInfo());
     $request->attributes->add($this->router->matchRequest($new_request));
     $this->currentRouteMatch->resetRouteMatch();
diff --git a/src/Plugin/facets/url_processor/QueryString.php b/src/Plugin/facets/url_processor/QueryString.php
--- a/src/Plugin/facets/url_processor/QueryString.php	(revision 297bc08b8054da8d20b728bcca3f6f0028e1819e)
+++ b/src/Plugin/facets/url_processor/QueryString.php	(date 1723051228741)
@@ -14,6 +14,8 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Session\Session;
+use Symfony\Component\HttpFoundation\Session\Storage\MockArraySessionStorage;

 /**
  * Query string URL processor.
@@ -281,6 +283,11 @@
     }

     $request = Request::create($facet_source_path);
+
+    $session = new Session(new MockArraySessionStorage());
+    $session->start();
+    $request->setSession($session);
+
     $request->attributes->set('_format', $this->request->get('_format'));
     $requestsByPath[$facet_source_path] = $request;
     return $request;