diff --git a/sources/download_manager.py b/sources/download_manager.py
index cdd7280..57126be 100644
--- a/sources/download_manager.py
+++ b/sources/download_manager.py
@@ -63,7 +63,7 @@ GITHUB_API_QUERIES = {
     "repository_commit_list": """
 {
     repository(owner: "$owner", name: "$name") {
-        refs(refPrefix: "refs/heads/", orderBy: {direction: DESC, field: TAG_COMMIT_DATE}, first: 100) {
+        refs(refPrefix: "refs/heads/", orderBy: {direction: DESC, field: TAG_COMMIT_DATE}, first: 10) {  # TODO: increase branch number with pagination
             edges {
                 node {
                     ... on Ref {
diff --git a/sources/main.py b/sources/main.py
index a8f78f3..30b5b9d 100644
--- a/sources/main.py
+++ b/sources/main.py
@@ -136,6 +136,9 @@ async def generate_commit_list(tz):
 
     for repository in repos:
         result = await DownloadManager.get_remote_graphql("repository_committed_dates", owner=repository["owner"]["login"], name=repository["name"], id=user.node_id)
+        if result["data"]["repository"] is None or result["data"]["repository"]["defaultBranchRef"] is None:
+            continue
+
         committed_dates = result["data"]["repository"]["defaultBranchRef"]["target"]["history"]["edges"]
         for committedDate in committed_dates:
             date = datetime.datetime.strptime(committedDate["node"]["committedDate"], "%Y-%m-%dT%H:%M:%SZ").replace(tzinfo=pytz.utc).astimezone(timezone(tz))