diff --git a/swh/storage/algos/snapshot.py b/swh/storage/algos/snapshot.py
--- a/swh/storage/algos/snapshot.py
+++ b/swh/storage/algos/snapshot.py
@@ -87,8 +87,9 @@
         snapshot = storage.snapshot_get_branches(
             snapshot_id, branches_count=branches_count
         )
+        if snapshot is None:
+            return None
         snapshot.pop("next_branch")
     else:
         snapshot = snapshot_get_all_branches(storage, snapshot_id)
-
-    return Snapshot.from_dict(snapshot)
+    return Snapshot.from_dict(snapshot) if snapshot else None
diff --git a/swh/storage/tests/algos/test_snapshot.py b/swh/storage/tests/algos/test_snapshot.py
--- a/swh/storage/tests/algos/test_snapshot.py
+++ b/swh/storage/tests/algos/test_snapshot.py
@@ -53,12 +53,13 @@
     yield no result
 
     """
+    # unknown origin so None
     assert snapshot_get_latest(swh_storage, "unknown-origin") is None
 
-    # no snapshot on origin visit then nothing is found
+    # no snapshot on origin visit so None
     origin = Origin.from_dict(data.origin)
     swh_storage.origin_add_one(origin)
-    swh_storage.origin_visit_add(
+    ov1 = swh_storage.origin_visit_add(
         [
             OriginVisit(
                 origin=origin.url,
@@ -68,8 +69,26 @@
                 snapshot=None,
             )
         ]
+    )[0]
+    assert snapshot_get_latest(swh_storage, origin.url) is None
+
+    # visit references a snapshot but the snapshot does not exist in backend for some
+    # reason
+    complete_snapshot = Snapshot.from_dict(data.complete_snapshot)
+    swh_storage.origin_visit_status_add(
+        [
+            OriginVisitStatus(
+                origin=origin.url,
+                visit=ov1.visit,
+                date=data.date_visit2,
+                status="partial",
+                snapshot=complete_snapshot.id,
+            )
+        ]
     )
+    # so we do not find it
     assert snapshot_get_latest(swh_storage, origin.url) is None
+    assert snapshot_get_latest(swh_storage, origin.url, branches_count=1) is None
 
 
 def test_snapshot_get_latest(swh_storage):