diff --git a/module/VuFind/src/VuFind/Session/Database.php b/module/VuFind/src/VuFind/Session/Database.php
index 7320f68ffc829e031020b6acf8771f827f88d117..752f7a251201833d6931d27617c9f1a115ad3a4b 100644
--- a/module/VuFind/src/VuFind/Session/Database.php
+++ b/module/VuFind/src/VuFind/Session/Database.php
@@ -55,7 +55,7 @@ class Database extends AbstractBase
                 ->readSession($sess_id, $this->lifetime);
         } catch (SessionExpiredException $e) {
             $this->destroy($sess_id);
-            return;
+            return '';
         }
     }