One or more error,

One or more of the error System. AggregateException:, - & gt; System.Net.Http.HttpRequestException:, an error occurred when sending a request - & gt; System.Net.WebException: underlying connection was closed: the connection was closed unexpectedly,
In System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult)
In System.Net.Http.HttpClientHandler.GetResponseCallback (IAsyncResult ar)
- at the end of the inner exception stack trace -- -- --
- at the end of the inner exception stack trace -- -- --
- & gt; Abnormal # 0 (internal) System.Net.Http.HttpRequestException:, an error occurred when sending a request - & gt; System.Net.WebException: underlying connection was closed: the connection was closed unexpectedly,
In System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult)
In System.Net.Http.HttpClientHandler.GetResponseCallback (IAsyncResult ar)


Note: 1. I take the corresponding data to postman test, found that the same problem also in
2. At first, can run for a period of time is something wrong with the
3. The service is mounted in the IIS running

4. Interestingly, I use the postman put the token value of the other party to head requests, said no response, but I take a small part of the token value, the server response