diff --git a/HTTPServer.cs b/HTTPServer.cs
index 8886b7d..ec33347 100644
--- a/HTTPServer.cs
+++ b/HTTPServer.cs
@@ -104,9 +104,10 @@ namespace ln.http
             }
 
             foreach (HTTPServerConnection connection in HTTPServerConnection.CurrentConnections)
-                connection.Abort();
+                connection?.Abort();
 
-            threadPool.Stop(true);
+            if (threadPool.State == PoolState.RUN)
+                threadPool.Stop(true);
         }
 
         private void AcceptConnections(TcpListener tcpListener)