Session state service failed - UWP - prism

Question

I am working on UWP application, using Prism 6.0
My application is working totally fine in both Debug and Release modes but when i am running Windows App Certification Kit on the app packages, I keep getting this Application error - "Session state service failed". I have never seen this exception when I am installing the app packages and running the app. But I get this exception every time when WACK is running the packages.
Because of this,
I am getting error in Windows App Certification Kit - Test Results.
The error are:
FAILED
Crashes and hangs
•Error Found: The crashes and hangs test detected the following errors:◦Executable C:\Program Files\WindowsApps\10486username.SongApp_1.1.0.0_x86__5q2wmk4fv784y\SongApp.exe was detected by Windows Error Reporting and experienced a crash or hang.
◦Application 10486username.SongApp_1.1.0.0_x86__5q2wmk4fv784y was detected by Windows Error Reporting and experienced a crash or hang.
•Impact if not fixed: An app that stops responding or crashes can cause data loss and is a poor user experience.
•How to fix: Investigate and debug the app to identify and fix the problem.
FAILED
Direct3D trim after suspend
•Error Found: The Direct3D Trim after Suspend test detected the following errors:◦Application App was not running at the end of the test. It likely crashed or was terminated for having become unresponsive.
•Impact if not fixed: If the app does not call Trim on its Direct3D device, the app will not release memory allocated for its earlier 3D work. This increases the risk of apps being terminated due to system memory pressure.
•How to fix: The app should call the Trim API on its IDXGIDevice3 interface anytime it is about to be suspended.

Answer 1

I've built a repro with the Prism sandbox app creating a new type as model, have it serialized on suspension and watch it crash through hitting Suspend and shutdown as application lifecycle event in the Debug location toolbar.
namespace HelloWorld.Models
{
public class MyModel
{
public MyModel() {}
public MyModel(string someText)
{
SomeText = someText;
}
public string SomeText { get; set; }
}
}
In the viewmodel:
[RestorableState]
public MyModel MyModel
{
get { return _myModel; }
set { SetProperty(ref _myModel, value); }
}
After some research, I managed to solve the crash by adding following lines in the runtime directives (Default.rd.xml) file:
<!-- Add your application specific runtime directives here. -->
<Namespace Name="HelloWorld.Models" Serialize="Required PublicAndInternal">
<Type Name="MyModel" Browse="Required Public" DataContractSerializer="Required Public"/>
</Namespace>
DataContractSerializer
Optional attribute. Controls policy for serialization that uses the System.Runtime.Serialization.DataContractSerializer class.
Source: MSDN