System.IO.FileNotFoundException: 'Could not load file or assembly

Question

I have an application in .net core. the application was running fine, but the error started coming after I installed

dotnet add package Microsoft.AspNetCore.Authentication.Negotiate --version 6.0.14

Once I installed this package and put this line of code in startup.cs file:

services.AddAuthentication(NegotiateDefaults.AuthenticationScheme)

       .AddNegotiate();

    services.AddAuthorization(options =>

    {

        options.FallbackPolicy = options.DefaultPolicy;

    });

I started getting this error:

System.IO.FileNotFoundException: 'Could not load file or assembly 'System.DirectoryServices.Protocols, Version=6.0.0.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.'

I installed this package when I saw the above error:

dotnet add package System.DirectoryServices --version 7.0.0

I am still getting this error. The error is coming in program.cs file. below is the screen shot of the error:

unfortunately, I dont see version 6.0.0.1 for System.directoryServices.protocols in nuget. Not sure, why the application is looking for 6.0.0.1 version when I have 7.0.0 version installed. Below is packages installed on my application:

Answer 1

Hi @Anjali Agarwal

Can you tell us your application type and version? Whether it is an Asp.net 6 MVC or Razor page application?

I create an Asp.net 6 MVC application to check it, after installing the "Microsoft.AspNetCore.Authentication.Negotiate 6.0.14" package, it will auto install the "System.DirectoryServices.Protocols 6.0.1" package, and after configuring the Negotiate authentication, your code works well without any error.

When installs the "Microsoft.AspNetCore.Authentication.Negotiate 6.0.14" package via NuGet, we can see its dependencies is: .Net 6.0 and "System.DirectoryServices.Protocols 6.0.1". After installing the Negotiate package via NuGet, it will also install the "System.DirectoryServices.Protocols 6.0.1".

So, you can try to re-install the Microsoft.AspNetCore.Authentication.Negotiate 6.0.14 package via NuGet.

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Dillion

Answer 2

The problem I have is that I am referencing System.DirectoryServices and System.DirectoryServices.AccountManagement in a library project that my web project uses.

If I try and set the version of these packages in the library project to anything other than 6.0.1 and 6.0.0 respectively I get the same error. Note that when I set these to 7.0.1 and 7.0.0 in the library project, the version of System.DirectoryServices.Protocols displayed as a dependency of Microsoft.AspNetCore.Authentication.Negotiate is no longer 6.0.1 but rather 7.0.0 and I get the error message.

I think somehow the Microsoft.AspNetCore.Authentication.Negoitiate package is not working with the 7.0.0 System.DirectoryServices package or it's wanting the earlier version but not getting it as a dependency since the solution is having a newer version via the library references.

Answer 3

In case you find this issue while trying to test in your deployed (published) environment, the issue in my case, was related to this setting you can specify while the publish is configured, the one that says "Trim Unused Code".

I guess I have the reference there but used with an Activator... idk... for some reason the publish determines it needs to trim this library. Set the checkbox in false and solved my problem.