diff --git a/install/lib/update.lib.php b/install/lib/update.lib.php
index 1bb0051d2d505de7d5082e3ea083daa94d84285d..581e2d69cb5b126c6c7844dca60e64d91b22cd19 100644
--- a/install/lib/update.lib.php
+++ b/install/lib/update.lib.php
@@ -394,6 +394,9 @@ function updateDbAndIni() {
 	unset($old_ini_array);
 	unset($tpl_ini_array);
 	unset($new_ini);
+
+	// Truncate sys_session
+	$inst->db->query('TRUNCATE ??', $conf['mysql']['database'].'sys_session');
 }