diff --git a/taskcluster/taskgraph/actions/cancel_all.py b/taskcluster/taskgraph/actions/cancel_all.py
index 8a5414f92970..fb698894be7f 100644
--- a/taskcluster/taskgraph/actions/cancel_all.py
+++ b/taskcluster/taskgraph/actions/cancel_all.py
@@ -26,6 +26,7 @@ def list_group(task_group_id, session):
     while True:
         url = base_url.format('task-group/{}/list'.format(task_group_id))
         response = session.get(url, stream=True, params=params)
+        response.raise_for_status()
         response = response.json()
         for task in [t['status'] for t in response['tasks']]:
             if task['state'] in ['running', 'pending', 'unscheduled']: