c# - HttpClient - A task was cancelled? -

it works fine when have 1 or 2 tasks throws error "a task cancelled" when have more 1 task listed.

list<task> alltasks = new list<task>(); alltasks.add(....); alltasks.add(....); task.waitall(alltasks.toarray(), configuration.cancellationtoken);   private static task<t> httpclientsendasync<t>(string url, object data, httpmethod method, string contenttype, cancellationtoken token) {     httprequestmessage httprequestmessage = new httprequestmessage(method, url);     httpclient httpclient = new httpclient();     httpclient.timeout = new timespan(constants.timeout);      if (data != null)     {         byte[] bytearray = encoding.ascii.getbytes(helper.tojson(data));         memorystream memorystream = new memorystream(bytearray);         httprequestmessage.content = new stringcontent(new streamreader(memorystream).readtoend(), encoding.utf8, contenttype);     }      return httpclient.sendasync(httprequestmessage).continuewith(task =>     {         var response = task.result;         return response.content.readasstringasync().continuewith(stringtask =>         {             var json = stringtask.result;             return helper.fromjson<t>(json);         });     }).unwrap(); } 

there's 2 reasons taskcanceledexception thrown:

1. something called cancel() on cancellationtokensource associated cancellation token before task completed.
2. the request timed out, i.e. didn't complete within timespan specified on httpclient.timeout.

my guess timeout. (if explicit cancellation, have figured out.) can more inspecting exception:

try {     var response = task.result; } catch (taskcanceledexception ex) {     // check ex.cancellationtoken.iscancellationrequested here.     // if false, it's pretty safe assume timeout. }