Windows IOT Raspberry Pi File Load Exception - windows-10-iot-core

Question

I have recently upgraded my Windows 10 machine to version 1709 and I have a problem debugging my app on my Raspberry pi.
The app is a background app and I get the following exception in the output window and the IBackgroundTask run method is never called.
Exception thrown: 'System.IO.FileLoadException' in System.Private.CoreLib.ni.dll
This is all I get - no idea on how to look further into this as there is no information on what it could not load.
I have tracked it down to me creating a class (simple creating am empty class is enough to show the error)
AquariumControllerPiLibrary.ABC c = new AquariumControllerPiLibrary.ABC();
This class is defined in a separate Class Library assembly.
The class source code is
using System;
namespace AquariumControllerPiLibrary
{
public class ABC
{
}
}
If I comment out the class the Run method executes and I can debug the application and I do not get the fileLoadException.
Any idea how I can find out what did not load?
The debug lines from the output window.
'backgroundTaskHost.exe' (CoreCLR: DefaultDomain): Loaded 'c:\data\Programs\WindowsApps\Microsoft.NET.CoreRuntime.1.1_1.1.25915.0_arm__8wekyb3d8bbwe\System.Private.CoreLib.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\AquariumControllerPi.winmd'. Symbols loaded.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\System.Runtime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'c:\data\Programs\WindowsApps\Microsoft.NET.CoreRuntime.1.1_1.1.25915.0_arm__8wekyb3d8bbwe\mscorlib.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\WinMetadata\Windows.winmd'. Module was built without symbols.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\System.Runtime.InteropServices.WindowsRuntime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\System.Threading.Tasks.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded
'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\ABC.dll'. Symbols loaded.
'backgroundTaskHost.exe' (CoreCLR: CoreCLR_UWP_Domain): Loaded 'C:\Data\Users\DefaultAccount\AppData\Local\DevelopmentFiles\AquariumControllerPIVS.Debug_ARM.CCROWE\System.Runtime.WindowsRuntime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Exception thrown: 'System.IO.FileLoadException' in System.Private.CoreLib.ni.dll