启动复杂的 ASP.NET Core 应用程序时无法加载文件或程序集

Question

I have complex ASP.NET Core solution, which consists of:

• Web part, which is ASP.NET Core Web Api project
• other parts, which are .NET Core class libraries

I want to add extension method to this class libraries, so they could register themselves, eg:

public static IServiceCollection AddThisLibrary(this IServiceCollection services)
{
    //a lot of addTransient...
    return services;
}

which I use in Startup class in ConfigureServices method, like this:

services.AddThisLibrary();

The problem is, that when I'm starting my application, it throws the exception:

An error occurred while starting the application. FileNotFoundException: Could not load file or assembly 'MyProject.API.Service, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified. MyProject.API.Web.Startup.ConfigureServices(IServiceCollection services)

for each my library.

I've checked /bin/Debug folder, where I have all my class libraries built in DLL , so I have no idea, why they can't be found.

How can I properly write such extension methods and remove that exception?

Answer 1

you should check that your dll is the same version as the one it is trying to load it, what i suggest is go to your reference, remove the existing one, go to your assembly remove it as well, then clean, then add it to your references again, build. Make sure you have one reference only.

Answer 2

My case may be specific a lot, but I faced this error when changed target from .net core 3.1 to .net 5. Some files in deploy folder remained from prevous deploys. I clean the folder an published once again.