diff --git a/swh/web/common/service.py b/swh/web/common/service.py
--- a/swh/web/common/service.py
+++ b/swh/web/common/service.py
@@ -970,16 +970,23 @@
             snapshot_id, branches_count=snapshot_sizes["alias"], target_types=["alias"]
         )
         for alias in aliases["branches"].values():
-            if lookup_snapshot(
-                snapshot_id,
-                branches_from=alias["target"],
-                branches_count=1,
-                target_types=["revision"],
-            ):
-                snapshot_sizes["revision"] += 1
-            else:
-                snapshot_sizes["release"] += 1
+            try:
+                for target_type in ("revision", "release"):
+                    snapshot = lookup_snapshot(
+                        snapshot_id,
+                        branches_from=alias["target"],
+                        branches_count=1,
+                        target_types=[target_type],
+                    )
+                    if snapshot and alias["target"] in snapshot["branches"]:
+                        snapshot_sizes[target_type] += 1
+            except NotFoundExc:
+                # aliased revision or release is missing in the snapshot
+                pass
         del snapshot_sizes["alias"]
+        # remove possible None key returned by snapshot_count_branches
+        # when null branches are present in the snapshot
+        snapshot_sizes.pop(None, None)
     return snapshot_sizes
 
 
diff --git a/swh/web/tests/browse/views/test_origin.py b/swh/web/tests/browse/views/test_origin.py
--- a/swh/web/tests/browse/views/test_origin.py
+++ b/swh/web/tests/browse/views/test_origin.py
@@ -732,6 +732,41 @@
     assert mock_service.lookup_snapshot_sizes.called
 
 
+@given(new_origin())
+def test_origin_empty_snapshot_null_revision(client, archive_data, new_origin):
+    snapshot = Snapshot(
+        branches={
+            b"HEAD": SnapshotBranch(
+                target="refs/head/master".encode(), target_type=TargetType.ALIAS,
+            ),
+            b"refs/head/master": None,
+        }
+    )
+    archive_data.origin_add([new_origin])
+    archive_data.snapshot_add([snapshot])
+    visit = archive_data.origin_visit_add(
+        [OriginVisit(origin=new_origin.url, date=now(), type="git",)]
+    )[0]
+    visit_status = OriginVisitStatus(
+        origin=new_origin.url,
+        visit=visit.visit,
+        date=now(),
+        status="partial",
+        snapshot=snapshot.id,
+    )
+    archive_data.origin_visit_status_add([visit_status])
+
+    url = reverse(
+        "browse-origin-directory", query_params={"origin_url": new_origin.url},
+    )
+    resp = client.get(url)
+    assert resp.status_code == 200
+    assert_template_used(resp, "browse/directory.html")
+    resp_content = resp.content.decode("utf-8")
+    assert re.search("snapshot.*is empty", resp_content)
+    assert not re.search("swh-tr-link", resp_content)
+
+
 @given(origin_with_releases())
 def test_origin_release_browse(client, archive_data, origin):
     snapshot = archive_data.snapshot_get_latest(origin["url"])