C#•3y ago•

2 replies

❔ How to dynamically load a different version of an assembly in the NET Core shared framework

Hi, I'm trying to dynamically load an assembly from a file 'System.Threading.Channels.dll', in a NET 6 project. But it throws an exception when trying to load the file.

Minimum reproducible example below.

Sandbox.csproj:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>
</Project>

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>
</Project>

Program.cs:

using System;
using System.IO;
using System.Reflection;

var directory = @"C:\path\to\directory\containing\the\file"; 
var dllName = "System.Threading.Channels.dll";
var assemblyPath = Path.Combine(directory, dllName);
Assembly.LoadFrom(assemblyPath); 
// System.IO.FileLoadException: 'Could not load file or assembly 'System.Threading.Channels, Version=7.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.'

using System;
using System.IO;
using System.Reflection;

var directory = @"C:\path\to\directory\containing\the\file"; 
var dllName = "System.Threading.Channels.dll";
var assemblyPath = Path.Combine(directory, dllName);
Assembly.LoadFrom(assemblyPath); 
// System.IO.FileLoadException: 'Could not load file or assembly 'System.Threading.Channels, Version=7.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.'

The

Assembly.LoadFrom

Assembly.LoadFrom

call throws the

FileLoadException

FileLoadException

in the comment above. Full stack trace:

   at System.Runtime.Loader.AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly)
   at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
   at System.Reflection.Assembly.LoadFrom(String assemblyFile)
   at Program.<Main>$(String[] args) in C:\Users\me\source\repos\Sandbox\Sandbox\Program.cs:line 8

   at System.Runtime.Loader.AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly)
   at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
   at System.Reflection.Assembly.LoadFrom(String assemblyFile)
   at Program.<Main>$(String[] args) in C:\Users\me\source\repos\Sandbox\Sandbox\Program.cs:line 8

DLL properties in screenshot below.

For this example, I can fix it if I add a

PackageReference

PackageReference

"System.Threading.Channels" Version="7.0.0"

"System.Threading.Channels" Version="7.0.0"

OR if I change the

TargetFramework

TargetFramework

net7.0

net7.0

. But neither of these options are possible in the actual codebase.

I can explain more about the actual context if needed, but right now I'm just trying to understand why this happens.

❔ How to dynamically load a different version of an assembly in the NET Core shared framework

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>
</Project>

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>
</Project>

Program.cs:

using System;
using System.IO;
using System.Reflection;

var directory = @"C:\path\to\directory\containing\the\file"; 
var dllName = "System.Threading.Channels.dll";
var assemblyPath = Path.Combine(directory, dllName);
Assembly.LoadFrom(assemblyPath); 
// System.IO.FileLoadException: 'Could not load file or assembly 'System.Threading.Channels, Version=7.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.'

using System;
using System.IO;
using System.Reflection;

var directory = @"C:\path\to\directory\containing\the\file"; 
var dllName = "System.Threading.Channels.dll";
var assemblyPath = Path.Combine(directory, dllName);
Assembly.LoadFrom(assemblyPath); 
// System.IO.FileLoadException: 'Could not load file or assembly 'System.Threading.Channels, Version=7.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.'

The

Assembly.LoadFrom

Assembly.LoadFrom

call throws the

FileLoadException

FileLoadException

in the comment above. Full stack trace:

   at System.Runtime.Loader.AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly)
   at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
   at System.Reflection.Assembly.LoadFrom(String assemblyFile)
   at Program.<Main>$(String[] args) in C:\Users\me\source\repos\Sandbox\Sandbox\Program.cs:line 8

   at System.Runtime.Loader.AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly)
   at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
   at System.Reflection.Assembly.LoadFrom(String assemblyFile)
   at Program.<Main>$(String[] args) in C:\Users\me\source\repos\Sandbox\Sandbox\Program.cs:line 8

DLL properties in screenshot below.

For this example, I can fix it if I add a

PackageReference

PackageReference

"System.Threading.Channels" Version="7.0.0"

"System.Threading.Channels" Version="7.0.0"

OR if I change the

TargetFramework

TargetFramework

net7.0

net7.0

. But neither of these options are possible in the actual codebase.

I can explain more about the actual context if needed, but right now I'm just trying to understand why this happens.

❔ How to dynamically load a different version of an assembly in the NET Core shared framework

❔ How to dynamically load a different version of an assembly in the NET Core shared framework

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