diff --git a/backend/api/routes/archives.py b/backend/api/routes/archives.py
index 8c9c713..0eb06cd 100644
--- a/backend/api/routes/archives.py
+++ b/backend/api/routes/archives.py
@@ -457,6 +457,8 @@ async def record_task_feedback(
     stmt: ExecutableStatement | None = None
     if payload.status == "succeeded":
         try:
+            if not payload.files:
+                raise OSError("No files in payload")
             # should we check for file["status"] == "uploaded"?
             file: dict = next(iter(payload.files.values()))
             filesize = file["size"]
diff --git a/backend/api/zimfarm.py b/backend/api/zimfarm.py
index 9db4fb9..3993647 100644
--- a/backend/api/zimfarm.py
+++ b/backend/api/zimfarm.py
@@ -46,6 +46,7 @@ class WebhookPayload(BaseModel):
     original_schedule_name: str
     updated_at: str
 
+
 class TokenData:
     """In-memory persistence of ZF credentials"""