diff --git a/lib/base.php b/lib/base.php
index 98a72cb901..bffae36261 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -539,7 +539,7 @@ class OC {
 				'setting locale to en_US.UTF-8/en_US.UTF8 failed. Support is probably not installed on your system',
 				OC_Log::ERROR);
 		}
-		if (OC_Config::getValue('installed', false)) {
+		if (OC_Config::getValue('installed', false) && !self::checkUpgrade(false)) {
 			if (OC_Appconfig::getValue('core', 'backgroundjobs_mode', 'ajax') == 'ajax') {
 				OC_Util::addScript('backgroundjobs');
 			}