diff --git a/api/dicom-web/controller/UPS-RS/service/cancel.service.js b/api/dicom-web/controller/UPS-RS/service/cancel.service.js
index 05a53537..5e6ed5ea 100644
--- a/api/dicom-web/controller/UPS-RS/service/cancel.service.js
+++ b/api/dicom-web/controller/UPS-RS/service/cancel.service.js
@@ -59,9 +59,10 @@ class CancelWorkItemService extends BaseWorkItemService {
 
     async addCancelEvent() {
         let hitSubscriptions = await this.getHitSubscriptions(this.workItem);
-        let aeTitles = hitSubscriptions.map(v => v.aeTitle);
-
-        this.addUpsEvent(UPS_EVENT_TYPE.CancelRequested, this.upsInstanceUID, this.cancelRequestBy(), aeTitles);
+        if (hitSubscriptions.length > 0 ) {
+            let aeTitles = hitSubscriptions.map(v => v.aeTitle);
+            this.addUpsEvent(UPS_EVENT_TYPE.CancelRequested, this.upsInstanceUID, this.cancelRequestBy(), aeTitles);
+        }
     }
 
     cancelRequestBy() {
diff --git a/api/dicom-web/controller/UPS-RS/service/create-workItem.service.js b/api/dicom-web/controller/UPS-RS/service/create-workItem.service.js
index 75e1c314..d3355c9d 100644
--- a/api/dicom-web/controller/UPS-RS/service/create-workItem.service.js
+++ b/api/dicom-web/controller/UPS-RS/service/create-workItem.service.js
@@ -86,7 +86,7 @@ class CreateWorkItemService extends BaseWorkItemService {
 
         let hitSubscriptions = await this.getHitSubscriptions(workItem);
 
-        if (hitSubscriptions) {
+        if (hitSubscriptions?.length > 0 ) {
             let hitSubscriptionAeTitleArray = hitSubscriptions.map(sub => sub.aeTitle);
             this.addUpsEvent(UPS_EVENT_TYPE.StateReport, workItem.upsInstanceUID, this.stateReportOf(await workItem.toDicomJson()), hitSubscriptionAeTitleArray);
             let assignedEventInformationArray = await this.getAssignedEventInformationArray(