FeatureLayer.LoadAsync() results in an NullReferenceException

MaxGlas

Hi,

I have a strange behaviour in my two test applications, both based on ArcGIS Runtime 100.2.

Both worked fine for many hours of developing, now I got an exception in both, even I did not change anything in one of these apps.

Both a very small and focused and have the same startup:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">public</SPAN> <SPAN class="token function">MainWindow</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="token function">InitializeComponent</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="token function">InitializeMap</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">}</SPAN>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">private</SPAN> <SPAN class="keyword token">async</SPAN> <SPAN class="keyword token">void</SPAN> <SPAN class="token function">InitializeMap</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Map map <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Map</SPAN><SPAN class="punctuation token">(</SPAN>Basemap<SPAN class="punctuation token">.</SPAN><SPAN class="token function">CreateTopographicVector</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; FeatureLayer featureLayer <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">FeatureLayer</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">Uri</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token"><SPAN>"</SPAN><A class="jive-link-external-small" href="https://community.esri.com/external-link.jspa?url=http%3A%2F%2Fsampleserver6.arcgisonline.com%2Farcgis%2Frest%2Fservices%2FWildfire%2FFeatureServer%2F2" target="_blank">http://sampleserver6.arcgisonline.com/arcgis/rest/services/Wildfire/FeatureServer/2</A><SPAN>"</SPAN></SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">await</SPAN> featureLayer<SPAN class="punctuation token">.</SPAN><SPAN class="token function">LoadAsync</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; map<SPAN class="punctuation token">.</SPAN>OperationalLayers<SPAN class="punctuation token">.</SPAN><SPAN class="token function">Add</SPAN><SPAN class="punctuation token">(</SPAN>featureLayer<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; MyMapView<SPAN class="punctuation token">.</SPAN>Map <SPAN class="operator token">=</SPAN> map<SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Both are now crashing in the same line 13, where the LoadAsync should be executed.

System.Net.Http.HttpRequestException occurred
  HResult=0x80131500
  Message=An error occurred while sending the request.
  Source=mscorlib
  StackTrace:
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at Esri.ArcGISRuntime.Internal.RequestRequiredHandler.<IssueRequestAndRespond>d__15.MoveNext()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at CustomGPSProvider.MainWindow.<InitializeMap>d__1.MoveNext() in C:\Users\mag\Documents\Visual Studio 2017\Projects\CustomGPSProvider\CustomGPSProvider\MainWindow.xaml.cs:line 37

Inner Exception 1:
WebException: The request was aborted: The request was canceled.

Inner Exception 2:
NullReferenceException: Object reference not set to an instance of an object.

The StackTrace for the Inner Exception 2 is:

   at System.Net.HttpWebRequest.CheckCacheUpdateOnResponse()
   at System.Net.HttpWebRequest.CheckResubmitForCache(Exception& e)
   at System.Net.HttpWebRequest.DoSubmitRequestProcessing(Exception& exception)
   at System.Net.HttpWebRequest.ProcessResponse()
   at System.Net.HttpWebRequest.SetResponse(CoreResponseData coreResponseData)

I have no idea what's wrong.

Any ideas?

Max

MaxGlas

Thanks for your answer, but the problem still occured.

But I found a reason for the problem: I had Fiddler running in the background, logging the REST calls. That was the trigger for the occuring problem - if I close Fiddler, everything works as expected.

I was searching in the web for the reason of this problem as I do not expect such interaction, and I found that issue from Morten Nielsen (he seems to be everywhere ) which exactly describes my problem.

It seems that there is a problem in the .NET Runtime Core and as far as I can see, this problem will be solved in nearer future.