angular 6 upgrade following error

[sajidali2444]

@asadsahi An unhandled exception occurred while processing the request. SocketException: No connection could be made because the target machine actively refused it System.Net.Http.ConnectHelper.ConnectAsync(string host, int port, CancellationToken cancellationToken)

HttpRequestException: No connection could be made because the target machine actively refused it System.Net.Http.ConnectHelper.ConnectAsync(string host, int port, CancellationToken cancellationToken)

HttpRequestException: Failed to proxy the request to http://localhost:4200/, because the request to the proxy target failed. Check that the proxy target server is running and accepting requests to http://localhost:4200/. any help, please?

[asadsahi]

upgraded to angular 6 now.

[im-siva]

SocketException: No connection could be made because the target machine actively refused it System.Net.Http.ConnectHelper.ConnectAsync(string host, int port, CancellationToken cancellationToken)

HttpRequestException: No connection could be made because the target machine actively refused it System.Net.Http.ConnectHelper.ConnectAsync(string host, int port, CancellationToken cancellationToken)

HttpRequestException: Failed to proxy the request to http://localhost:4200/, because the request to the proxy target failed. Check that the proxy target server is running and accepting requests to http://localhost:4200/.

The underlying exception message was 'No connection could be made because the target machine actively refused it'.Check the InnerException for more details. Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task baseUriTask, CancellationToken applicationStoppingToken, bool proxy404s)

getting this error in angular 6