diff --git a/lib/private/session/internal.php b/lib/private/session/internal.php
index 9d3b9cb81ba0b3278f9e18420b3fc56d187d96f3..42ec9606dc9defacd5c6482097dccbe05c925c2c 100644
--- a/lib/private/session/internal.php
+++ b/lib/private/session/internal.php
@@ -54,4 +54,7 @@ class Internal extends Memory {
 		parent::close();
 	}
 
+    public function reopen() {
+        throw new \Exception('The session cannot be reopened - reopen() is ony to be used in unit testing.');
+    }
 }