diff --git a/filemanager/inc/class.filemanager_ui.inc.php b/filemanager/inc/class.filemanager_ui.inc.php
index 9e55df5cea..3d124a7f2a 100644
--- a/filemanager/inc/class.filemanager_ui.inc.php
+++ b/filemanager/inc/class.filemanager_ui.inc.php
@@ -1193,7 +1193,7 @@ class filemanager_ui
 			//_debug_array($content);
 			$path =& $content['path'];
 
-			$button = @key($content['button']);
+			$button = @key($content['button'] ?? []);
 			unset($content['button']);
 			if(!$button && $content['sudo'] && $content['sudouser'])
 			{