hi, how to control this ex?

[mark-wang-sh]

An exception of type 'System.Net.Sockets.SocketException' occurred in System.dll but was not handled in user code

Additional information: No connection could be made because the target machine actively refused it

This exception cannot be captured by trycatch

[mark-wang-sh]

try
            {
                XmlConfigurator.Configure();
                logger.Debug("Sample debug message");
                logger.Info("Sample informational message");
                logger.Error("Error");
            }
            catch (Exception ex)
            {
                logger.Error("ttt");
            }

[marksl]

Possibly your call to logger.Error("ttt") in the catch block is thrown the unhandled exception.