diff --git a/admin/inc/class.admin_mail.inc.php b/admin/inc/class.admin_mail.inc.php
index 338d659cf1..db74bc11db 100644
--- a/admin/inc/class.admin_mail.inc.php
+++ b/admin/inc/class.admin_mail.inc.php
@@ -1285,7 +1285,7 @@ class admin_mail
 		{
 			$sel_options['ident_email_alias'] = array_merge(
 				array('' => $content['mailLocalAddress'].' ('.lang('Default').')'),
-				array_combine($content['mailAlternateAddress'], $content['mailAlternateAddress']));
+				array_combine($content['mailAlternateAddress'] ?? [], $content['mailAlternateAddress'] ?? []));
 			// if admin explicitly set a non-alias, we need to add it to aliases to keep it after storing signature by user
 			if ($content['ident_email'] !== $content['mailLocalAddress'] && !isset($sel_options['ident_email_alias'][$content['ident_email']]))
 			{
diff --git a/calendar/inc/class.calendar_uiforms.inc.php b/calendar/inc/class.calendar_uiforms.inc.php
index 3b95d480f0..a71a56af23 100644
--- a/calendar/inc/class.calendar_uiforms.inc.php
+++ b/calendar/inc/class.calendar_uiforms.inc.php
@@ -1924,7 +1924,7 @@ class calendar_uiforms extends calendar_ui
 				$sel_options['owner'][$uid] = $this->bo->participant_name($uid);
 			}
 		}
-		$content['no_add_alarm'] = !count($sel_options['owner']);	// no rights to set any alarm
+		$content['no_add_alarm'] = empty($sel_options['owner']) || !count((array)$sel_options['owner']);	// no rights to set any alarm
 		if (!$event['id'])
 		{
 			$etpl->set_cell_attribute('button[new_alarm]','type','checkbox');