diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index eba6617a1..9b048ed96 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -75,8 +75,6 @@ jobs:
 
       - name: Check out code into the Go module directory
         uses: actions/checkout@v2
-        with:
-          submodules: true
 
       - name: Cache Go Dependencies
         uses: actions/cache@v2
diff --git a/pkg/controller/core.oam.dev/v1alpha2/applicationconfiguration/apply.go b/pkg/controller/core.oam.dev/v1alpha2/applicationconfiguration/apply.go
index 854541c4e..697a60659 100644
--- a/pkg/controller/core.oam.dev/v1alpha2/applicationconfiguration/apply.go
+++ b/pkg/controller/core.oam.dev/v1alpha2/applicationconfiguration/apply.go
@@ -83,6 +83,9 @@ type workloads struct {
 }
 
 func (a *workloads) Apply(ctx context.Context, status []v1alpha2.WorkloadStatus, w []Workload, ao ...apply.ApplyOption) error {
+	if len(w) == 0 {
+		return errors.New("The number of workloads in appConfig is 0 ")
+	}
 	// they are all in the same namespace
 	var namespace = w[0].Workload.GetNamespace()
 	for _, wl := range w {