Index: zabbix-3.4.12-1+buster/frontends/php/include/classes/api/services/CMaintenance.php
===================================================================
--- zabbix-3.4.12-1+buster.orig/frontends/php/include/classes/api/services/CMaintenance.php
+++ zabbix-3.4.12-1+buster/frontends/php/include/classes/api/services/CMaintenance.php
@@ -276,7 +276,6 @@ class CMaintenance extends CApiService {
 		// hosts permissions
 		$options = [
 			'hostids' => $hostids,
-			'editable' => true,
 			'output' => ['hostid'],
 			'preservekeys' => true
 		];
@@ -289,7 +288,6 @@ class CMaintenance extends CApiService {
 		// groups permissions
 		$options = [
 			'groupids' => $groupids,
-			'editable' => true,
 			'output' => ['groupid'],
 			'preservekeys' => true
 		];
@@ -458,7 +456,6 @@ class CMaintenance extends CApiService {
 			'selectGroups' => ['groupid'],
 			'selectHosts' => ['hostid'],
 			'selectTimeperiods' => API_OUTPUT_EXTEND,
-			'editable' => true,
 			'preservekeys' => true
 		]);
 
@@ -580,7 +577,6 @@ class CMaintenance extends CApiService {
 			$db_hosts = API::Host()->get([
 				'output' => [],
 				'hostids' => $hostids,
-				'editable' => true,
 				'preservekeys' => true
 			]);
 
@@ -598,7 +594,6 @@ class CMaintenance extends CApiService {
 			$db_groups = API::HostGroup()->get([
 				'output' => [],
 				'groupids' => $groupids,
-				'editable' => true,
 				'preservekeys' => true
 			]);
 
Index: zabbix-3.4.12-1+buster/frontends/php/maintenance.php
===================================================================
--- zabbix-3.4.12-1+buster.orig/frontends/php/maintenance.php
+++ zabbix-3.4.12-1+buster/frontends/php/maintenance.php
@@ -105,7 +105,6 @@ if (isset($_REQUEST['maintenanceid'])) {
 	$dbMaintenance = API::Maintenance()->get([
 		'output' => API_OUTPUT_EXTEND,
 		'selectTimeperiods' => API_OUTPUT_EXTEND,
-		'editable' => true,
 		'maintenanceids' => getRequest('maintenanceid'),
 	]);
 	if (empty($dbMaintenance)) {
@@ -412,7 +411,6 @@ if (!empty($data['form'])) {
 			'maintenanceids' => $data['maintenanceid'],
 			'real_hosts' => true,
 			'output' => ['hostid'],
-			'editable' => true
 		]);
 		$data['hostids'] = zbx_objectValues($data['hostids'], 'hostid');
 
@@ -458,7 +456,6 @@ if (!empty($data['form'])) {
 
 	// get groups
 	$data['all_groups'] = API::HostGroup()->get([
-		'editable' => true,
 		'output' => ['groupid', 'name'],
 		'real_hosts' => true,
 		'preservekeys' => true
@@ -475,7 +472,6 @@ if (!empty($data['form'])) {
 	$data['hosts'] = API::Host()->get([
 		'output' => ['hostid', 'name'],
 		'real_hosts' => true,
-		'editable' => true,
 		'groupids' => $data['twb_groupid']
 	]);
 
@@ -483,7 +479,6 @@ if (!empty($data['form'])) {
 	$hostsSelected = API::Host()->get([
 		'output' => ['hostid', 'name'],
 		'real_hosts' => true,
-		'editable' => true,
 		'hostids' => $data['hostids']
 	]);
 	$data['hosts'] = array_merge($data['hosts'], $hostsSelected);
@@ -532,7 +527,6 @@ else {
 		'search' => [
 			'name' => ($filter['name'] === '') ? null : $filter['name']
 		],
-		'editable' => true,
 		'sortfield' => $sortField,
 		'sortorder' => $sortOrder,
 		'limit' => $config['search_limit'] + 1