System.PlatformNotSupportedException while debugging on iPad

System.PlatformNotSupportedException while debugging on iPad

I use Xamarin.iOS 6.4.2 (latest beta version) with Visual Studio to
develop an iPad application.
There are 3 projects in my solution : a PCL with Tasks, async/await and
generics, a WPF project and an iOS project (I also use MvvmCross).
Launching the iOS app on simulator works fine. But when I try to launch
the app on the device, it installs the app but then it crash, debug stop
and this exception appear :
System.PlatformNotSupportedException: This platform is not supported
And when I try to launch the installed app on the device, the app crash
after 2-3 seconds (cannot do anything during this time) and the iPad
system log indicates this :
Aug 9 17:02:17 unknown MyProj[16849] <Warning>:
Unhandled Exception:
0 MyProj 0x009edd4b
mono_handle_exception_internal_first_pass + 1594
1 MyProj 0x009ee9b5
mono_handle_exception_internal + 840
2 MyProj 0x009eef9f mono_handle_exception
+ 10
3 MyProj 0x009dc839
mono_arm_throw_exception + 128
4 MyProj 0x00319cb8 throw_exception + 68
at
System.Runtime.CompilerServices.AsyncMethodBuilderCore/MoveNextRunner.Run
() <IL 0x00051, 0x001fc>
at Microsoft.Runtime.CompilerServices.TaskAwaiter.RunNoException
(System.Action) <IL 0x00001, 0x0007c>
at
Microsoft.Runtime.CompilerServices.TaskAwaiter/<>c__DisplayClassa.<OnCompletedInternal>b__4
(System.Threading.Tasks.Task) <IL 0x00012, 0x000a8>
at System.Threading.Tasks.TaskActionInvoker/ActionTaskInvoke.Invoke
(System.Threading.Tasks.Task,object,System.Threading.Tasks.Task) [0x00000]
in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskActionInvoker.cs:112
at System.Threading.Tasks.Task.InnerInvoke () [0x0000b] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:505
at System.Threading.Tasks.Task.ThreadStart () [0x0009d] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:407
at System.Threading.Tasks.Task.Execute () [0x00000] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:471
at System.Threading.Tasks.TaskScheduler.TryExecuteTask
(System.Threading.Tasks.Task) [0x0001f] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskScheduler.cs:125
at System.Threading.Tasks.TpScheduler.TryExecuteTaskInline
(System.Threading.Tasks.Task,bool) [0x00014] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TpScheduler.cs:78
at System.Threading.Tasks.TaskScheduler.RunInline
(System.Threading.Tasks.Task,bool) [0x00000] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskScheduler.cs:138
at System.Threading.Tasks.Task.RunSynchronouslyCore
(System.Threading.Tasks.TaskScheduler) [0x00015] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:221
at System.Threading.Tasks.TaskContinuation.Execute () [0x0004a] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskContinuation.cs:107
at System.Threading.Tasks.Task.ProcessCompleteDelegates () [0x0001b] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:557
at System.Threading.Tasks.Task.Finish () [0x000d4] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:544
at System.Threading.Tasks.Task`1.TrySetResult (TResult) <0x000b4>
at System.Threading.Tasks.TaskCompletionSource`1.TrySetResult (TResult)
<0x00048>
at System.Threading.Tasks.TaskCompletionSource`1.SetResult (TResult)
<0x00024>
at System.Threading.Tasks.TaskExtensionsImpl.SetResult<TResult>
(System.Threading.Tasks.Task`1<TResult>,System.Threading.Tasks.TaskCompletionSource`1<TResult>)
<0x000b0>
at System.Threading.Tasks.TaskExtensionsImpl.<Cont`1>m__7D<TResult>
(System.Threading.Tasks.Task`1<TResult>,object) <0x00050>
at
System.Threading.Tasks.TaskActionInvoker/ActionTaskObjectInvoke`1.Invoke
(System.Threading.Tasks.Task,object,System.Threading.Tasks.Task) <0x00064>
at System.Threading.Tasks.Task.InnerInvoke () [0x0000b] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:505
at System.Threading.Tasks.Task.ThreadStart () [0x0009d] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:407
at System.Threading.Tasks.Task.Execute () [0x00000] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:471
at System.Threading.Tasks.TaskScheduler.TryExecuteTask
(System.Threading.Tasks.Task) [0x0001f] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskScheduler.cs:125
at System.Threading.Tasks.TpScheduler.TryExecuteTaskInline
(System.Threading.Tasks.Task,bool) [0x00014] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TpScheduler.cs:78
at System.Threading.Tasks.TaskScheduler.RunInline
(System.Threading.Tasks.Task,bool) [0x00000] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskScheduler.cs:138
at System.Threading.Tasks.Task.RunSynchronouslyCore
(System.Threading.Tasks.TaskScheduler) [0x00015] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:221
at System.Threading.Tasks.TaskContinuation.Execute () [0x0004a] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/TaskContinuation.cs:107
at System.Threading.Tasks.Task.ProcessCompleteDelegates () [0x0001b] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:557
at System.Threading.Tasks.Task.Finish () [0x000d4] in
/Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:544
at System.Threading.Tasks.Task`1.TrySetResult (TResult) <0x000b4>
at System.Threading.Tasks.TaskCompletionSource`1.TrySetResult (TResult)
<0x00048>
at System.Threading.Tasks.TaskCompletionSource`1.SetResult (TResult)
<0x00024>
at System.Threading.Tasks.TaskFactory`1.InnerInvoke
(System.Threading.Tasks.TaskCompletionSource`1<TResult>,System.Func`2<System.IAsyncResult,
TResult>,System.IAsyncResult) <0x00058>
at
System.Threading.Tasks.TaskFactory`1/<FromAsyncBeginEnd>c__AnonStorey3F.<>m__31
(System.IAsyncResult) <0x00070>
at System.Net.WebAsyncResult.CB (object) [0x00000] in
/Developer/MonoTouch/Source/mono/mcs/class/System/System.Net/WebAsyncResult.cs:151
at (wrapper runtime-invoke) object.runtime_invoke_dynamic
(intptr,intptr,intptr,intptr) <0x000c8>
Does someone has already had this problem and know how to resolve it?
Thanks in advance