diff --git a/service/repo/repo.go b/service/repo/repo.go
index 1835a37f..9a578c51 100644
--- a/service/repo/repo.go
+++ b/service/repo/repo.go
@@ -57,7 +57,9 @@ func (s *service) List(ctx context.Context, user *core.User) ([]*core.Repository
 			return nil, err
 		}
 		for _, src := range result {
-			repos = append(repos, convertRepository(src, s.visibility, s.trusted))
+			if src != nil {
+				repos = append(repos, convertRepository(src, s.visibility, s.trusted))
+			}
 		}
 		opts.Page = meta.Page.Next
 		opts.URL = meta.Page.NextURL
diff --git a/service/repo/repo_test.go b/service/repo/repo_test.go
index 210d3d49..299c79a1 100644
--- a/service/repo/repo_test.go
+++ b/service/repo/repo_test.go
@@ -246,3 +246,44 @@ func TestList_RefreshErr(t *testing.T) {
 		t.Errorf("Expect error refreshing token")
 	}
 }
+
+func TestListWithNilRepo(t *testing.T) {
+	controller := gomock.NewController(t)
+	defer controller.Finish()
+
+	mockUser := &core.User{}
+	mockRepos := []*scm.Repository{
+		{
+			Namespace: "octocat",
+			Name:      "hello-world",
+		},
+		nil,
+	}
+
+	mockRepoService := mockscm.NewMockRepositoryService(controller)
+	mockRepoService.EXPECT().List(gomock.Any(), gomock.Any()).Return(mockRepos, &scm.Response{}, nil)
+
+	mockRenewer := mock.NewMockRenewer(controller)
+	mockRenewer.EXPECT().Renew(gomock.Any(), mockUser, false)
+
+	client := new(scm.Client)
+	client.Repositories = mockRepoService
+
+	want := []*core.Repository{
+		{
+			Namespace:  "octocat",
+			Name:       "hello-world",
+			Slug:       "octocat/hello-world",
+			Visibility: "public",
+		},
+	}
+
+	service := New(client, mockRenewer, "", false)
+	got, err := service.List(noContext, mockUser)
+	if err != nil {
+		t.Error(err)
+	}
+	if diff := cmp.Diff(got, want); diff != "" {
+		t.Errorf(diff)
+	}
+}
diff --git a/service/syncer/syncer.go b/service/syncer/syncer.go
index af148fc3..d65bc374 100644
--- a/service/syncer/syncer.go
+++ b/service/syncer/syncer.go
@@ -16,6 +16,7 @@ package syncer
 
 import (
 	"context"
+	"runtime/debug"
 	"strings"
 	"time"
 
@@ -67,6 +68,7 @@ func (s *Synchronizer) Sync(ctx context.Context, user *core.User) (*core.Batch,
 		if err := recover(); err != nil {
 			logger = logger.WithField("error", err)
 			logger.Errorln("syncer: unexpected panic")
+			debug.PrintStack()
 		}
 
 		// when the synchronization process is complete