HttpClient is throwing a TaskCanceledException on timeout in some circumstances. This is happening for us when the server is under heavy load. We were able to work around by increasing the default timeout. The following MSDN forum thread captures the essence of the experienced issue: https://social.msdn.microsoft.com/Forums/en-US/d8d87789-0ac9-4294-84a0-91c9fa27e353/bug-in-httpclientgetasync-should-throw-webexception-not-taskcanceledexception?forum=netfxnetcom&prof=required

Thanks