diff --git a/AIParkingApplication/ApiController.cs b/AIParkingApplication/ApiController.cs
index 2550e67..9042b1a 100644
--- a/AIParkingApplication/ApiController.cs
+++ b/AIParkingApplication/ApiController.cs
@@ -13,17 +13,15 @@ namespace AIParkingApplication
         private const int MAX_REQUEST = 3;
         private HttpClient httpClient;
         private bool isHttpClientDisposabled;
-        private int numberOfRetry;
 
         public ApiController(string baseAddress, int numberOfRetry = 5)
         {
             httpClient = new HttpClient
             {
                 BaseAddress = new Uri(baseAddress),
-                Timeout = TimeSpan.FromSeconds(5)
+                Timeout = TimeSpan.FromSeconds(1)
             };
             isHttpClientDisposabled = false;
-            this.numberOfRetry = numberOfRetry;
         }
 
         ~ApiController()
@@ -91,7 +89,7 @@ namespace AIParkingApplication
                 {
                     response = await httpClient.PostAsJsonAsync("/api/check-card", request);
                     requestCounter += 1;
-                    Thread.Sleep(100);
+                    await Task.Delay(100);
                 }
                 while (response.StatusCode != HttpStatusCode.OK && requestCounter < MAX_REQUEST);
 
@@ -102,7 +100,7 @@ namespace AIParkingApplication
             catch (Exception ex)
             {
                 Console.WriteLine($"CheckCard Exception:\t{DateTime.Now.GetTimeFormatted()} \t {ex.Message}");
-                return new CardInformation();
+                return null;
             }
         }
 
@@ -135,9 +133,8 @@ namespace AIParkingApplication
                 {
                     response = await httpClient.PostAsJsonAsync("/api/save-logs", request);
                     requestCounter += 1;
-                    Thread.Sleep(100);
-                }
-                while (response.StatusCode != HttpStatusCode.OK && requestCounter < MAX_REQUEST);
+                    await Task.Delay(100);
+                } while (response.StatusCode != HttpStatusCode.OK && requestCounter < MAX_REQUEST);
                 response.EnsureSuccessStatusCode();
                 SaveLogRespone saveLogRespone = await response.Content.ReadAsAsync<SaveLogRespone>();
                 return saveLogRespone;
diff --git a/AIParkingApplication/LaneIn.cs b/AIParkingApplication/LaneIn.cs
index 4baf402..ae6f274 100644
--- a/AIParkingApplication/LaneIn.cs
+++ b/AIParkingApplication/LaneIn.cs
@@ -56,6 +56,11 @@ namespace AIParkingApplication
             }
             ClearPlateAndOverviewImage();
             var cardInfoResult = await apiController.GetCardInformation(cardNumber);
+            if (cardInfoResult == null)
+            {
+                lblStatusInfo.UpdateLabel("KHÔNG THỂ KẾT NỐI SERVER", Color.Purple);
+                return;
+            }
             if (!cardInfoResult.IsValid)
             {
                 lblStatusInfo.UpdateLabel("THẺ KHÔNG HỢP LỆ", Color.Purple);
diff --git a/AIParkingApplication/LaneOut.cs b/AIParkingApplication/LaneOut.cs
index 4bc3efb..489db20 100644
--- a/AIParkingApplication/LaneOut.cs
+++ b/AIParkingApplication/LaneOut.cs
@@ -59,6 +59,11 @@ namespace AIParkingApplication
             ClearPlateAndOverviewImage();
             ClearPlateAndOverviewImageIn();
             var cardInfoResult = await apiController.GetCardInformation(cardNumber);
+            if (cardInfoResult == null)
+            {
+                lblStatusInfo.UpdateLabel("KHÔNG THỂ KẾT NỐI SERVER", Color.Purple);
+                return;
+            }
             if (!cardInfoResult.IsValid)
             {
                 lblStatusInfo.UpdateLabel("THẺ KHÔNG HỢP LỆ", Color.Purple);