diff --git a/application/src/main/java/org/thingsboard/server/controller/UserController.java b/application/src/main/java/org/thingsboard/server/controller/UserController.java
index d49b2b04df..002b27d265 100644
--- a/application/src/main/java/org/thingsboard/server/controller/UserController.java
+++ b/application/src/main/java/org/thingsboard/server/controller/UserController.java
@@ -105,6 +105,7 @@ import static org.thingsboard.server.controller.ControllerConstants.USER_ID_PARA
 import static org.thingsboard.server.controller.ControllerConstants.USER_SORT_PROPERTY_ALLOWABLE_VALUES;
 import static org.thingsboard.server.controller.ControllerConstants.USER_TEXT_SEARCH_DESCRIPTION;
 import static org.thingsboard.server.controller.ControllerConstants.UUID_WIKI_LINK;
+import static org.thingsboard.server.dao.entity.BaseEntityService.NULL_CUSTOMER_ID;
 
 @RequiredArgsConstructor
 @RestController
@@ -439,32 +440,28 @@ public class UserController extends BaseController {
             @RequestParam(required = false) String sortProperty,
             @ApiParam(value = SORT_ORDER_DESCRIPTION, allowableValues = SORT_ORDER_ALLOWABLE_VALUES)
             @RequestParam(required = false) String sortOrder) throws ThingsboardException {
-        try {
-            checkParameter("alarmId", strAlarmId);
-            AlarmId alarmEntityId = new AlarmId(toUUID(strAlarmId));
-            Alarm alarm = checkAlarmId(alarmEntityId, Operation.READ);
-            SecurityUser currentUser = getCurrentUser();
-            TenantId tenantId = currentUser.getTenantId();
-            CustomerId originatorCustomerId = entityService.fetchEntityCustomerId(tenantId, alarm.getOriginator()).get();
-            PageLink pageLink = createPageLink(pageSize, page, textSearch, sortProperty, sortOrder);
-            PageData<User> pageData;
-            if (Authority.TENANT_ADMIN.equals(currentUser.getAuthority())) {
-                if (alarm.getCustomerId() == null) {
-                    pageData = userService.findTenantAdmins(tenantId, pageLink);
-                } else {
-                    ArrayList<CustomerId> customerIds = new ArrayList<>(Collections.singletonList(new CustomerId(CustomerId.NULL_UUID)));
-                    if (!CustomerId.NULL_UUID.equals(originatorCustomerId.getId())) {
-                        customerIds.add(originatorCustomerId);
-                    }
-                    pageData = userService.findUsersByCustomerIds(tenantId, customerIds, pageLink);
-                }
+        checkParameter("alarmId", strAlarmId);
+        AlarmId alarmEntityId = new AlarmId(toUUID(strAlarmId));
+        Alarm alarm = checkAlarmId(alarmEntityId, Operation.READ);
+        SecurityUser currentUser = getCurrentUser();
+        TenantId tenantId = currentUser.getTenantId();
+        CustomerId originatorCustomerId = entityService.fetchEntityCustomerId(tenantId, alarm.getOriginator()).orElse(NULL_CUSTOMER_ID);
+        PageLink pageLink = createPageLink(pageSize, page, textSearch, sortProperty, sortOrder);
+        PageData<User> pageData;
+        if (Authority.TENANT_ADMIN.equals(currentUser.getAuthority())) {
+            if (alarm.getCustomerId() == null) {
+                pageData = userService.findTenantAdmins(tenantId, pageLink);
             } else {
-                pageData = userService.findCustomerUsers(tenantId, alarm.getCustomerId(), pageLink);
+                ArrayList<CustomerId> customerIds = new ArrayList<>(Collections.singletonList(NULL_CUSTOMER_ID));
+                if (!CustomerId.NULL_UUID.equals(originatorCustomerId.getId())) {
+                    customerIds.add(originatorCustomerId);
+                }
+                pageData = userService.findUsersByCustomerIds(tenantId, customerIds, pageLink);
             }
-            return pageData.mapData(user -> new UserEmailInfo(user.getId(), user.getEmail(), user.getFirstName(), user.getLastName()));
-        } catch (Exception e) {
-            throw handleException(e);
+        } else {
+            pageData = userService.findCustomerUsers(tenantId, alarm.getCustomerId(), pageLink);
         }
+        return pageData.mapData(user -> new UserEmailInfo(user.getId(), user.getEmail(), user.getFirstName(), user.getLastName()));
     }
 
     @ApiOperation(value = "Save user settings (saveUserSettings)",
diff --git a/application/src/test/java/org/thingsboard/server/controller/UserControllerTest.java b/application/src/test/java/org/thingsboard/server/controller/UserControllerTest.java
index 28bb987257..d37b4ebe5b 100644
--- a/application/src/test/java/org/thingsboard/server/controller/UserControllerTest.java
+++ b/application/src/test/java/org/thingsboard/server/controller/UserControllerTest.java
@@ -49,6 +49,7 @@ import org.thingsboard.server.common.data.page.PageLink;
 import org.thingsboard.server.common.data.security.Authority;
 import org.thingsboard.server.common.data.settings.StarredDashboardInfo;
 import org.thingsboard.server.common.data.settings.UserDashboardsInfo;
+import org.thingsboard.server.dao.device.DeviceService;
 import org.thingsboard.server.dao.exception.DataValidationException;
 import org.thingsboard.server.dao.service.DaoSqlTest;
 import org.thingsboard.server.dao.user.UserDao;
@@ -81,6 +82,9 @@ public class UserControllerTest extends AbstractControllerTest {
     @Autowired
     private UserDao userDao;
 
+    @Autowired
+    private DeviceService deviceService;
+
     static class Config {
         @Bean
         @Primary
@@ -740,6 +744,43 @@ public class UserControllerTest extends AbstractControllerTest {
         Assert.assertEquals(expectedCustomerUserIds, loadedUserIds);
     }
 
+    @Test
+    public void testGetUsersForDeletedAlarmOriginator() throws Exception {
+        loginTenantAdmin();
+
+        String email = "testEmail1";
+        for (int i = 0; i < 45; i++) {
+            User customerUser = createCustomerUser( customerId);
+            customerUser.setEmail(email + StringUtils.randomAlphanumeric((int) (5 + Math.random() * 10)) + "@thingsboard.org");
+            doPost("/api/user", customerUser, User.class);
+        }
+
+        Device device = new Device();
+        device.setName("testDevice");
+        device.setCustomerId(customerId);
+        Device savedDevice = doPost("/api/device", device, Device.class);
+
+        Alarm alarm = createTestAlarm(savedDevice);
+
+        deviceService.deleteDevice(tenantId, savedDevice.getId());
+
+        List<UserId> loadedUserIds = new ArrayList<>();
+        PageLink pageLink = new PageLink(33, 0);
+        PageData<UserEmailInfo> pageData;
+        do {
+            pageData = doGetTypedWithPageLink("/api/users/assign/" + alarm.getId().getId().toString() + "?",
+                    new TypeReference<>() {}, pageLink);
+            loadedUserIds.addAll(pageData.getData().stream().map(UserEmailInfo::getId)
+                    .collect(Collectors.toList()));
+            if (pageData.hasNext()) {
+                pageLink = pageLink.nextPageLink();
+            }
+        } while (pageData.hasNext());
+
+        Assert.assertEquals(1, loadedUserIds.size());
+        Assert.assertEquals(tenantAdminUserId, loadedUserIds.get(0));
+    }
+
     @Test
     public void testDeleteUserWithDeleteRelationsOk() throws Exception {
         loginSysAdmin();