System.Net.Http.HttpRequestException Error while copying content to a stream

Question

I am using the HttpClient class in .NET Framework 4.5.2.

I calling PostAsync against a third party web service. 80% of the time this post works, 20%

Answer 1

I had a similar problem with the use of a shared HttpClient connecting to a server for REST calls. The problem ended up being a mismatch between the KeepAlive timeout on the client and server. The client side timeout is set by the MaxServicePointIdleTime setting on the ServicePointManager and defaults to 100s. The server side idle timeout was set to a shorter value in our server.

Having a shorter timeout on the server as compared to the client resulted in the server sporadically closing a connection just when the client was attempting to connect. This resulted in the reported exception.

Note that I ultimately found the problem because I also received this exception under the same conditions:

System.Net.WebException: The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.