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Created attachment 9358 [details]
Xamarin version information
When using HttpClient to make web requests on an iPhone I intermittently get the exception below.
A few notes:
1. I am reusing HttpClient object but never run concurrent requests on the same HttpClient.
2. I have a pool of HttpClients that usually ranges from 2-3 depending on usage.
3. I patterned my code based on a blog entry by Henrik on how to use HttpClient using ContinueWith.
4. I create a new task for each request prior to making request.
5. If I repeat the request immediately with the same HttpClient, it works.
6. It seems to always fail on the PostAsync, not the later
Steps to reproduce: Repeated PostAsync requests on the same HttpClient.
The exception is this:
*****MakeWebReqeust NullReferenceException for url = chat/receive: message = 'Object reference not set to an instance of an object' elapsed time = 505
stack trace = at System.Net.Http.HttpClientHandler.CreateResponseMessage (System.Net.HttpWebResponse wr, System.Net.Http.HttpRequestMessage requestMessage, CancellationToken cancellationToken) [0x00000] in ///Library/Frameworks/Xamarin.iOS.framework/Versions/184.108.40.206/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClientHandler.cs:290
at System.Net.Http.HttpClientHandler+<SendAsync>c__async0.MoveNext () [0x0041f] in ///Library/Frameworks/Xamarin.iOS.framework/Versions/220.127.116.11/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClientHandler.cs:355
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:62
at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1+ConfiguredTaskAwaiter[System.Net.Http.HttpResponseMessage].GetResult () [0x00000] in <filename unknown>:0
at System.Net.Http.HttpClient+<SendAsyncWorker>c__async0.MoveNext () [0x000a9] in ///Library/Frameworks/Xamarin.iOS.framework/Versions/18.104.22.168/src/mono/mcs/class/System.Net.Http/System.Net.Http/HttpClient.cs:273
*** This bug has been marked as a duplicate of bug 22724 ***
@Marek Safar - I am familiar with the bug you reference but I don't believe this is a duplicate of that. I am NOT running concurrent requests. I am reusing the same HTTPClient object but I never run concurrent requests.
#22724 does not need to involve concurrent request. I believe the issues was address. If you have repro which does still exhibits the problem, please reopen the bug report.
@marek Safar - #22724 specifically refers to android. Does the fix apply to iOS as well?
yes, the code is exactly same
@Marek Safar - thanks. So, how do I get the fix? Is this on the alpha, beta, or stable channels?
Yes, the fix should be included in latest Xamarin.iOS alpha