diff --git a/CHANGELOG.md b/CHANGELOG.md
index d43f36ad..117fa1e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Enable email notification step by default on Helm by @vadimkerr ([#2975](https://github.com/grafana/oncall/pull/2975))
 - Handle slack resolution note errors consistently ([#2976](https://github.com/grafana/oncall/pull/2976))
 
+### Fixed
+
+- Don't update Slack user groups for deleted organizations by @vadimkerr ([#2985](https://github.com/grafana/oncall/pull/2985))
+
 ## v1.3.35 (2023-09-05)
 
 ### Fixed
diff --git a/engine/apps/slack/tasks.py b/engine/apps/slack/tasks.py
index d669be75..4c00a4d9 100644
--- a/engine/apps/slack/tasks.py
+++ b/engine/apps/slack/tasks.py
@@ -451,7 +451,12 @@ def start_update_slack_user_group_for_schedules():
     from apps.slack.models import SlackUserGroup
 
     user_group_pks = (
-        SlackUserGroup.objects.filter(oncall_schedules__isnull=False).distinct().values_list("pk", flat=True)
+        SlackUserGroup.objects.filter(
+            oncall_schedules__isnull=False,  # has oncall schedules connected
+            oncall_schedules__organization__deleted_at__isnull=True,  # organization is not deleted
+        )
+        .distinct()
+        .values_list("pk", flat=True)
     )
 
     for user_group_pk in user_group_pks:
diff --git a/engine/apps/slack/tests/test_user_group.py b/engine/apps/slack/tests/test_user_group.py
index 614b6a44..6626f862 100644
--- a/engine/apps/slack/tests/test_user_group.py
+++ b/engine/apps/slack/tests/test_user_group.py
@@ -2,9 +2,11 @@ from unittest.mock import PropertyMock, patch
 
 import pytest
 
-from apps.schedules.models.on_call_schedule import OnCallScheduleQuerySet
+from apps.schedules.models.on_call_schedule import OnCallScheduleQuerySet, OnCallScheduleWeb
 from apps.slack.client import SlackClientWithErrorHandling
 from apps.slack.models import SlackUserGroup
+from apps.slack.tasks import start_update_slack_user_group_for_schedules, update_slack_user_group_for_schedules
+from apps.user_management.models import Organization
 
 
 @pytest.mark.django_db
@@ -67,3 +69,25 @@ def test_update_oncall_members(
         with patch.object(SlackUserGroup, "update_members") as update_members_mock:
             user_group.update_oncall_members()
             update_members_mock.assert_called()
+
+
+@pytest.mark.django_db
+def test_start_update_slack_user_group_for_schedules_organization_deleted(
+    make_organization_with_slack_team_identity, make_slack_user_group, make_schedule
+):
+    organization, slack_team_identity = make_organization_with_slack_team_identity()
+    user_group = make_slack_user_group(slack_team_identity)
+    make_schedule(organization, schedule_class=OnCallScheduleWeb, user_group=user_group)
+
+    # check user group is updated
+    with patch.object(update_slack_user_group_for_schedules, "delay") as mock:
+        start_update_slack_user_group_for_schedules()
+        mock.assert_called_once_with(user_group_pk=user_group.pk)
+
+    # soft delete the organization
+    Organization.objects.filter(pk=organization.pk).delete()
+
+    # check user group is not updated for deleted organization
+    with patch.object(update_slack_user_group_for_schedules, "delay") as mock:
+        start_update_slack_user_group_for_schedules()
+        mock.assert_not_called()