diff --git a/ui/include/classes/screens/CScreenDiscovery.php b/ui/include/classes/screens/CScreenDiscovery.php
index 9c25a52813d..a87b16ac6bf 100644
--- a/ui/include/classes/screens/CScreenDiscovery.php
+++ b/ui/include/classes/screens/CScreenDiscovery.php
@@ -92,6 +92,15 @@ class CScreenDiscovery extends CScreenBase {
 		// services
 		$services = [];
 		foreach ($dservices as $dservice) {
+			// DEBUG
+			if (!array_key_exists($dservice['dcheckid'], $dchecks)) {
+				error_log('ERROR: '
+					.'dcheckid '.json_encode($dservice['dcheckid'])
+					.', dserviceid '.json_encode($dservice['dserviceid'])
+					.', dservice hosts'.json_encode($dservice['hosts'])
+				);
+			}
+			// DEBUG
 			$key_ = $dchecks[$dservice['dcheckid']]['key_'];
 			if ($key_ !== '') {
 				if (array_key_exists($key_, $macros)) {