using assembly.load with a specific file location

Question

I have the current file structure in my Visual Studio project:

MyProject/
- MyStartupProject/
  - bin/
    - Debug/
  - Program.cs
- DependencyProject/
  - bin/
  - dlls/
    - MyAssembly.dll
  - Code.cs

My Main() function is inside MyProject/MyStartupProject/Program.cs. Inside Code.cs is a line var assembly = Assembly.Load("MyAssembly");, which is supposed to load MyProject/DependencyProject/dlls/MyAssembly.dll, but instead it causes the error

System.IO.FileNotFoundException: 'Could not load file or assembly 'MyAssembly' or one of its dependencies.
The system cannot find the file specified.'

However, everything runs perfectly fine if I copy MyAssembly.dll into MyProject/MyStartupProject/bin/Debug. How do I fix this reference so the project can find it under the dlls directory?

you need to add it as a project resource, then it'll get copied across the profiles — jazb, Jan 27 '22 at 07:24
The build system doesn't know that you have a dependency on this DLL, so won't copy it for you. You [have to help](https://stackoverflow.com/a/21760295/17034). Or use LoadFrom() instead of Load(). Or just use a project reference and use types from the assembly in your code. — Hans Passant, Jan 27 '22 at 08:53
Glad to know you've found the solution to resolve this issue! Please consider accepting it as an answer to change its status to Answered. It will also help others to solve a similar issue. See [can I answer my own question..](https://stackoverflow.com/help/self-answer), Just a reminder :) — Jiale Xue - MSFT, Feb 10 '22 at 08:31

Jiale Xue - MSFT · Answer 1 · 2022-01-28T03:02:53.850

1

Try to Change the status of `MyAssembly.dll` to `Copy if new`.

Update:

Add file

Update2:Is there a way I can get it to copy straight into Debug/ without moving the original out of the dlls/ directory?

Two solutions:

Change var assembly = Assembly.Load("MyAssembly"); to var assembly = Assembly.LoadFrom("dlls\MyAssembly.dll");.
Add

<Target Name="BeforeBuild">
        <Copy
            SourceFiles="dlls\MyAssembly.dll"
            DestinationFolder="bin\Debug"
        />
    </Target>

to csproj.

csproj:

Unload Project:

2.Double-click Project:

edited Jan 28 '22 at 03:02

answered Jan 27 '22 at 07:59

Jiale Xue - MSFT

1,570
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I have a "Copy Local" which is already set to true, but no "Copy to Output Directory" option. I am using .NET Framework if that makes a difference – wheeeee Jan 27 '22 at 08:05
Please check my updates, did you right-click on this property? I am .Net Framework 4.8. – Jiale Xue - MSFT Jan 27 '22 at 08:25
I found that the assembly was copied to `MyStartupProject/bin/Debug/dlls/MyAssembly.dll`, rather than `MyStartupProject/bin/Debug/MyAssembly.dll` and the error persists. Is there a way I can get it to copy straight into `Debug/` without moving the original out of the `dlls/` directory? – wheeeee Jan 27 '22 at 20:42
Please check my updates, If you don't mind, you could click '✔' to mark my reply as the accepted answer. It will also help others to solve the similar issue. – Jiale Xue - MSFT Jan 28 '22 at 03:03
I found another way to resolve my error so I did not get a chance to try your update – wheeeee Jan 31 '22 at 23:32
@wheeeee If you try to check my update you will find your answer in my latest update. – Jiale Xue - MSFT Feb 01 '22 at 01:13

score 1 · Answer 2 · answered Jan 31 '22 at 23:32

I resolved my issue by adding the following to my DependencyProject.csproj

<ContentWithTargetPath Include="dlls\MyAssembly.dll">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <TargetPath>MyAssembly.dll</TargetPath>
</ContentWithTargetPath>

This causes the dlls to be automatically copied into MyStartupProject/bin/Debug/.