Cannot get Type declared in a .NET Framework assembly from a .NET Core 2 assembly

Question

I have a .NET Core 2 console app which is performing some maintenance/upgrade work on the DB underlying a ASP.NET website running on .NET Framework 4.7.1.

The console app needs to read in the assembly-qualified type names of classes which are declared in the .NET Framework assemblies. It does this using Type.GetType("[assembly-qualified name]";

This code works perfectly well for the built-in .NET types but it throws an exception when it comes to types defined in our own assemblies. Confusingly, I can declare a variable of one of these types in the .NET Core console app but I'm unable to instantiate a Type object referencing the same type.

For example, this works...

var cs = Common.CustomerManagement.Person.CustomerStatus.ApprovedCustomer;

but this...

var ct = Type.GetType("Common.CustomerManagement.Person+CustomerStatus, Common, Version=1.0.6793.16016, Culture=neutral, PublicKeyToken=null;");

...throws the exception...

System.IO.FileLoadException: The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)
at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type, ObjectHandleOnStack keepalive)
at System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName)
at System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark)
at System.Type.GetType(String typeName)

I realise that in the code which works I'm referencing an enum on the type and in the code which doesn't work I'm referencing just the type, but the working code shows that the referenced .NET Framework assembly can be loaded whereas the non-working code suggests that the type is not available to the .NET Core console app.

It is not happy about the assembly name you provided. "1.0.6793.16016" is a very ugly version number, never let the build system auto-increment the [AssemblyVersion] when you need to make reflection work. You'll inevitably get that number wrong in your code. Odd problem to have in a .netcore project btw, I'd have to guess you are hoofing this yourself instead of using Project > Properties > Package in Visual Studio. — Hans Passant
You're right - I found that once I removed the version number from the assembly-qualified name it was accepted. — awj
@HansPassant - If you change your comment to a suggested answer then I'll mark it as accepted. — awj
I just have no idea where that fugly version number came from. Tell us about it in your own answer. — Hans Passant

awj awj · Accepted Answer · 2018-08-07T12:25:02

The problem was that the type name is the Type.AssemblyQualifiedName which includes a version number.

It's the version number which was causing the problem. Once I removed the version number and left the other information in the type name, it worked.

Cannot get Type declared in a .NET Framework assembly from a .NET Core 2 assembly

1 Answers