diff --git a/app/controllers/consultation/consultation_controller.php b/app/controllers/consultation/consultation_controller.php
index dc7fd6e6a90385a9bb46bf917173860b87aaf593..1c25a9bddc75bee80a4fab2e25dbce6d45420209 100644
--- a/app/controllers/consultation/consultation_controller.php
+++ b/app/controllers/consultation/consultation_controller.php
@@ -79,6 +79,10 @@ abstract class ConsultationController extends AuthenticatedController
 
         $block = ConsultationBlock::find($block_id);
 
+        if (!$block || !$block->range) {
+            throw new Exception(_('Dieser Terminblock ist ungültig.'));
+        }
+
         if (!$block->range->isAccessibleToUser()) {
             throw new AccessDeniedException();
         }