I'm having trouble understanding what exactly this exception is telling me. The project has two modules which both use regions.
They both load usercontrols into a single region called NavigationRegion. NavigationRegion is defined in the Shell view xaml file as so:
Whenever the module initializes, I call the following line of code in my project:
I get this exception immediately:
An exception occurred while initializing module 'Module'. - The exception message was: An exception has occurred while trying to add a view to region 'NavigationRegion'. - The most likely causing exception
was was: 'System.InvalidOperationException: Sequence contains more than one element at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source) at Microsoft.Practices.Prism.MefExtensions.MefServiceLocatorAdapter.DoGetInstance(Type
serviceType, String key) in c:\release\WorkingDir\PrismLibraryBuild\PrismLibrary\Desktop\Prism.MefExtensions\MefServiceLocatorAdapter.cs:line 73 at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String
In general, what is causing this exception?