Ignore unknown notification recipients

application/src/main/java/org/thingsboard/server/controller/NotificationController.java

@@ -300,9 +300,15 @@ public class NotificationController extends BaseController {
         request.setOriginatorEntityId(user.getId());
         List<NotificationTarget> targets = request.getTargets().stream()
                 .map(NotificationTargetId::new)
-                .map(targetId -> notificationTargetService.findNotificationTargetById(user.getTenantId(), targetId))
+                .map(targetId -> {
+                    NotificationTarget target = notificationTargetService.findNotificationTargetById(user.getTenantId(), targetId);
+                    if (target == null) {
+                        throw new IllegalArgumentException("Notification target for id " + targetId + " not found");
+                    }
+                    return target;
+                })
                 .sorted(Comparator.comparing(target -> target.getConfiguration().getType()))
-                .collect(Collectors.toList());
+                .toList();
 
         NotificationRequestPreview preview = new NotificationRequestPreview();
 

application/src/main/java/org/thingsboard/server/service/notification/DefaultNotificationCenter.java

@@ -73,6 +73,7 @@ import org.thingsboard.server.service.telemetry.AbstractSubscriptionService;
 import org.thingsboard.server.service.ws.notification.sub.NotificationRequestUpdate;
 import org.thingsboard.server.service.ws.notification.sub.NotificationUpdate;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
@@ -115,12 +116,23 @@ public class DefaultNotificationCenter extends AbstractSubscriptionService imple
         } else {
             notificationTemplate = request.getTemplate();
         }
-        if (notificationTemplate == null) throw new IllegalArgumentException("Template is missing");
+        if (notificationTemplate == null) {
+            throw new IllegalArgumentException("Template is missing");
+        }
 
         Set<NotificationDeliveryMethod> deliveryMethods = new HashSet<>();
-        List<NotificationTarget> targets = request.getTargets().stream().map(NotificationTargetId::new)
+        List<NotificationTarget> targets = new ArrayList<>();
-                .map(id -> notificationTargetService.findNotificationTargetById(tenantId, id))
+        for (UUID targetId : request.getTargets()) {
-                .collect(Collectors.toList());
+            NotificationTarget target = notificationTargetService.findNotificationTargetById(tenantId, new NotificationTargetId(targetId));
+            if (target != null) {
+                targets.add(target);
+            } else {
+                log.debug("Unknown notification target {} in request {}", targetId, request);
+            }
+        }
+        if (targets.isEmpty()) {
+            throw new IllegalArgumentException("No recipients chosen");
+        }
 
         NotificationRuleId ruleId = request.getRuleId();
         notificationTemplate.getConfiguration().getDeliveryMethodsTemplates().forEach((deliveryMethod, template) -> {