first, index will be -1.

v2rayN/v2rayN/Forms/MainForm.cs

@@ -1338,6 +1338,8 @@ namespace v2rayN.Forms
             return 0;
         }
         private void tsbSubUpdate_Click(object sender, EventArgs e)
+        {
+            try
             {
                 VmessItem item = config.vmess[config.index];
                 var remarks = item.remarks;
@@ -1361,6 +1363,11 @@ namespace v2rayN.Forms
                 };
                 handle.UpdateSubscriptionProcess(config, _updateUIAndReselect);
             }
+            catch
+            {
+                UpdateSubscriptionProcess();
+            }
+        }
         /// <summary>
         /// the subscription update process
         /// </summary>