Windows 10 version 1903 update (NET Framework 4.8) breaking Prism 6.3 - prism

Question

First off, we are well aware that this isn't strictly speaking a Prism 6.3 issue; what we're looking for (in case a solution isn't straightforward) are pointers to a solution to the problem -thanks in advance btw-, which is:
Windows 10 version 1903, via .NET Framework 4.8 inclusion, breaks our otherwise perfectly functioning, tried-and-true, production-deployed Prism 6.3-based commercial software. We're using Prism (Core), Prism.WPF, and Prism.MEF (all v6.3). What we get (source code later) is the following runtime error whenever we try to instantiate a registered View:
Prism.Regions.RegionNavigationService.CreateNewRegionItem(String candidateTargetContract) throws an InvalidOperationException: Cannot create navigation target 'xyzView'. Activation error ocurred while tring to get instance of type Object, key 'xyzView'.
Inner exception stems from Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key), which throws an ActivationException: Activation error ocurred while tring to get instance of type Object, key 'xyzView'.
Devil's in the details so here's some relevant code (xyzView = ExpedicionView or ExpedicionMaestroView, both trigger the Exception):
[ModuleExport(typeof(ExpedicionModulo))]
[Export(typeof(IMenu))]
public class ExpedicionModulo : IModule, IMenu
{
[Import]
public IRegionManager RegionManager;
[Import]
public ILoggerFacade Logger;
[ImportingConstructor]
public ExpedicionModulo(IRegionManager regionManager, ILoggerFacade logger)
{
Logger = logger;
RegionManager = regionManager;
// irrelevant (for our purposes) code omitted here
}
public void Initialize()
{
// Here's how we register views for main region
RegionManager.RegisterViewWithRegion(RegionNames.MainContentRegion, typeof(ExpedicionView));
RegionManager.RegisterViewWithRegion(RegionNames.MainContentRegion, typeof(MaestroExpedicionView));
// Some more registering for our dialog region
RegionManager.RegisterViewWithRegion(RegionNames.DialogRegion, typeof(ExpedicionDetalleView));
// other views registered in the very same fashion
Logger.Log("Expedition Module initialized", Category.Info, Priority.None);
}
We invoke RequestNavigate in this bit of code here:
[Export]
[PartCreationPolicy(CreationPolicy.Shared)]
public class ShellViewModel : BaseViewModel
{
public IRibbonPrincipal RibbonPrincipal { get; set; }
private readonly InteractionRequest<Confirmation> _confirmationInteractionRequest;
private readonly InteractionRequest<Notification> _notificationInteractionRequest;
private string _seccionActiva;
private string _subseccionActiva;
private IRegionManager _regionManager;
[ImportingConstructor]
public ShellViewModel(IRegionManager regionManager, IEventAggregator eventAggregator, ILoggerFacade logger)
: this(eventAggregator, logger)
{
try
{
_regionManager = regionManager;
_regionManager.RegisterViewWithRegion(RegionNames.MainContentRegion, typeof(PrincipalView));
}
catch (Exception ex)
{
this.LoggerError(ex.Message);
}
}
public ShellViewModel(IEventAggregator eventAggregator, ILoggerFacade logger)
: base(eventAggregator, logger)
{
try
{
// Some irrelevant (to our purposes) initialization code omitted here
New = new DelegateCommand(() => { }, () => { return false; }); // etc.
_confirmationInteractionRequest = new InteractionRequest<Confirmation>();
_notificationInteractionRequest = new InteractionRequest<Notification>();
// Events code omitted for brevity sake
EventAggregator.GetEvent<MessageBoxEvent>().Subscribe(ShowMessageBox, ThreadOption.PublisherThread, false); // etc.
// View loading wireup
CambioSeccion = new DelegateCommand<object>(OnCambioSeccion);
CambioSubseccion = new DelegateCommand<object[]>(OnCambioSubseccion);
// some more irrelevant (to our purposes) code omitted here.
}
catch (Exception ex)
{
this.LoggerError(ex.Message);
}
}
/// <summary>
/// This is where we instantiate the View (WAI in .NET Framework <=4.7.2)
/// </summary>
/// <param name="objeto"></param>
private void OnCambioSeccion(object objeto)
{
// Ribbon menu handling here
RibbonPrincipal.ResetRibbon();
IIdentifyViewModel ivm = null;
// We are passing the View's name via clicked TreeViewItem in this case (param objeto)
TreeViewItem treeViewItem = (TreeViewItem)objeto;
if (treeViewItem != null && !string.IsNullOrEmpty(treeViewItem.Name))
{
_seccionActiva = treeViewItem.Name;
// Now we build the actual RequestNavigate invoke
// In our case, _seccionActiva would equal "Expedicion" or "MaestroExpedicion"
_regionManager.RequestNavigate(RegionNames.MainContentRegion, new Uri("/" + _seccionActiva + "View", UriKind.Relative), (r) =>
{
if (!r.Result.HasValue || !r.Result.Value)
{
// error handling code here
}
else
{
ivm = ((FrameworkElement)_regionManager.Regions[RegionNames.MainContentRegion].ActiveViews.First()).DataContext as IIdentifyViewModel;
}
});
// Some event triggering here
if (ivm != null)
{
Seccion.Cambio(EventAggregator, ivm.ID);
}
}
}
Sorry for the long winded post, and thanks in advance.

Answer 1

#mcandal thanks for the write-up. This looks like a recent issue introduced in .NET Framework 4.8 that we have seen with the patterns and practices activation code. The underlying issue is that in 4.8 the constructors for types were returned in a different order resulting in the patterns and practices choice of the first (eg. ctors[0]) sometimes no longer being correct.
There are a few workarounds as we work through a fix in an upcoming release.
This issue only impacts assemlbies that are ngen'd.
Workarounds:
1) Disable ngen for the assembly containing the type:
<configuration>
<runtime>
<disableNativeImageLoad>
<assemblyIdentity name="assembly_name" />
</disableNativeImageLoad>
</runtime>
</configuration>
2) For the type that is being activated only have 1 ctor (the documentation for the patterns and practices assumes there is only 1 ctor)
3) Choose the other provided activation models where you pass in the types of the parameters, to avoid the ambiguity.
As I mentioned, we are working on a fix and if you would like to discuss further you can submit a VS Feedback item and link to this post and we can continue the discussion there.