Goal:
From a .NET 4.7 console app, using reflection with Assembly.GetType(), I am trying extract the Type of a netstandard 2.0 class from Assembly X. Then I want to create an instance of this Type with Activator.CreateInstance().
What I am trying to do:
However, this assembly X has a dependency to netstandard 2.0. To be able to get the Type, netstandard dependency has to be loaded into the AppDomain. That's why when the AppDomain is requesting the netstandard assembly through the AssemblyResolve event, I simply load the dll like this :
var netStandardDllPath = #"C:\Users\xxx\.nuget\packages\NETStandard.Library.2.0.0-preview1-25301-01\build\netstandard2.0\ref\netstandard.dll";
return Assembly.LoadFrom(netStandardDllPath);
Which throws:
System.BadImageFormatException: 'Could not load file or assembly
'file:///C:\Users\vincent.lerouvillois.nuget\packages\NETStandard.Library.2.0.0-preview1-25301-01\build\netstandard2.0\ref\netstandard.dll'
or one of its dependencies. Reference assemblies should not be loaded
for execution. They can only be loaded in the Reflection-only loader
context. (Exception from HRESULT: 0x80131058)'
Inner Exception: BadImageFormatException: Cannot load a reference
assembly for execution.
What I know:
I know that they want us to load the DLL with Assembly.ReflectionOnlyLoadFrom. But doing that will prevent me from instanciate the type with Activator.CreateInstance(). See Microsoft official post
Also, I tried referencing the Nuget packages NETStandard.Library 2.0.0-preview1-25301-01 and NETStandard.Library.NETFramework 2.0.0-preview1-25305-02 in my console app so it would have the netstandard 2.0 libraries referenced, but it didn't change anything.
Question:
Does anyone would know if there is a proper way to load that dll without error, or maybe if this is a bug, or else? Or why this kind of dll is not able to load for execution?
The netstandard.dll you are trying to load is a reference assembly that which cannot be loaded for runtime on .NET Framework as pointed out by others. However if you need to resolve that dependency you will need to runtime version that maps to the framework you are trying to run on.
For .NET Standard support we are including them as part of the msbuild extensions that ship with VS so you will want to get the version of netstandard.dll from there. Depending on which version of VS2017 you have installed it should be somewhere like C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\lib\netstandard.dll or from the .NET Core 2.0 SDK you can find it C:\Program Files\dotnet\sdk\2.0.0\Microsoft\Microsoft.NET.Build.Extensions\net461\lib\netstandard.dll
Try using one of those versions in your scenario.
Wow. I just spent several hours tracking the cause of this "could not load ... netstandard" error down.
For me, the problem was that my .NET Framework project (which references both .NET Framework and .NET Standard libraries) was built with .NET Framework 4.7.2 and the system where I was deploying and running it did not have 4.7.2 installed.
Deploying a very small Console project with the same basic structure and references and executing that in a Command window finally revealed the correct error, in a pop-up, that .NET Framework 4.7.2 was missing.
If you're struggling with this particular error, make sure you have the necessary .NET Framework installed.
Set Copy Local to true in netstandard.dll properties.
Open Solution Explorer and right click on netstandard.dll.
Set Copy Local to true.
You can't load a reference assembly.
.NET Standard is a collection of APIs that must be provided by .NET Standard compatible implementations.
A reference assembly only contains contracts. This means that it contains no implementation. The assembly you are trying to load contains the .NET Standard 2.0 contracts.
A contract looks like this: https://github.com/dotnet/standard/blob/master/netstandard/ref/mscorlib.cs
EDIT: .NET Framework 4.7 implements .NET Standard 2.0, so you shouldn't need to load any assembly to use Activator.CreateInstance() to instantiate a .NET Standard type.
NETStandard 2.0.0-preview1 in not compatibility with net461 and net47.
but for realese .NET Core SDK 2.0 assemblies (as well as 2.0.0-preview2)
var netStandardDllPath = #"c:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.netcore.app\2.0.0\ref\netcoreapp2.0\netstandard.dll";
Console.WriteLine(Assembly.LoadFrom(netStandardDllPath).FullName);
all is ok.
But if you steel need to load preview1 libraries, maybe you should to use netstandard2.0 instead net471.
For me solved doing the following:
1 - Installed latest .Net Framework on server.
2 - Updated windows server and my local machine.
3 - Went to Manage Nuget Package and updated all references on the update tab.
Perhaps only doing step 3 can solve in your case
In case if IBM Message Queue references are used in the project solution, this exception indicates that the DLL used for refering MQ classes are incompatible with the host(server) .NET version installed.
In this scenario, either we need to update server with latest update and make sure .NET latest version is available or use lower version of IBM Message queue DLL as reference.
Old version DLL - amqmdnet.dll (no new features will be introduced by IBM as not in support)
Latest version DLL - amqmdnetstd.dll (to run IBM MQ classes for .NET Standard, you must install Microsoft .NET Core)
Install NetStandard.Library 2.0.0.0 from NuGet , It works for me. when I downgrade .net framework 4.6.1 to 4.6.0
If you are having this issue for a project that used to work, try deleting the bin and obj folders since caching can cause this, too.
I have a problem when referencing a DLL.
I do everything correctly:
1.The DLL is built with no errors
2.I add it as a reference in my other solution
However the system doesn't recognize it and I get the folowing error message:
"Type or namespace could not be found.Are you missing an assembly reference?"
I read on various forums and adjusted the .NET version of the DLL to match the .NET 4 on my project.I tried all versions 4/4-Client Profile/4.5 and none of them fixed the problem.The DLL,I checked with .NET Reflector and everything is there and working as it's supposed to.
Can you help me with this issue?
I am having a visual studio 2010 window service application in .net framework version 3.5 but I need to use a dll in my service which was built in .net framework version 4.0.So I have upgraded my version to 4.0 but while installing my service i am having system.BadImageFormatException.How to fix this.Please suggest some solution.
This is the error message I am getting
Error 1001.Exception occurred while initializing the installation: System.BadImageFormatExceptio: could not load file or assembly 'file://C:.....exe' or more or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded.
Thanks in advance
The application and the DLL (including all dependencies of each) must all be either 32-bit or 64-bit. Most likely, the binaries you are using are not. To fix the problem build or otherwise obtain access to the correct binaries.
If this is not the problem, the "remarks" section of the documentation lists all the reasons that can cause this exception to be thrown, including solutions for each.
i'm trying to develop an application but then these warnings popped out. I have tried disabling my anti-virus (Avira) but it still won't work.
Warning 1 Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not load file or assembly 'MyAssembly.dll' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded. ConsoleApplication1
Warning 2 The referenced component 'MyAssembly' could not be found.
Can anybody please help me? Thanks!
What .NET runtime version is your application being developed with?
If the error is to be trusted, your project is say a .NET 3.5 (2.0 runtime) project but the MyAssembly library is developed in .NET 4.0 resulting in the error you see.
You cannot reference newer runtime version assemblies in an older runtime version project. You'd have to "upgrade" your project to at least match the framework version of the assembly given to you.
Right click on your project file and choose properties. Depending on what version of Visual Studio you are using this screen may look different, but go to the application tab and see what the target framework is.
Then go to the assembly you referenced in your references and check the "Runtime Version" in the properties section:
We have a function in a VS2005 project that loads assembles and get type information from them . It does not instantiate these types though. We tried to load some assembles that are compiled in 2010, but keep getting the following exception.
"Could not load file or assembly '2010ClassLibrary' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded."
Is there anyway to get around this?
If you are not using any .Net 4 features in your code in the VS2010 solution, then set your target for the solution to be .Net 2.0 instead. This will allow you to reference it in VS2005. .Net 3.5 can be used in VS2008.
you could run the app under .net 4 and then the code to load the assembly should be fine.
http://msdn.microsoft.com/en-us/library/f4kkd0k5.aspx