System.TypeLoadException

You can use JetBrains dotPeek (free), Reflector, ILDASM or ILSpy to get the assembly version.

You usually can find ILDASM in C:\Program Files (x86)\Microsoft SDKs\Windows\v8.1A\bin\NETFX 4.5.1 Tools\ildasm.exe (where v8.1A is the version of the Windows SDK installed).

ILDASM:

Reflector:

By Patrick Hofman. Read the original answer on Stack Overflow.

Important: This will occur when a service or dependency can't be resolved. Run your code in debug mode or you can see what is missing using -verbose with your migration command. If you can resolve dependencies and run the code without errors, you can proceed with the migrations. However, if you can't do that or want to run migrations separately from the app logic, please follow the instructions.

EF calls CreateWebHostBuilder or BuildWebHost without running Main. So Iconfiguration is null.

Create a new class which inherited from IDesignTimeDbContextFactory.

public class YourDbContext : DbContext
{
//Dbcontext implementation
}

public class YourDbContextFactory : IDesignTimeDbContextFactory<YourDbContext>
{
    public YourDbContext CreateDbContext(string[] args)
    {
        var optionsBuilder = new DbContextOptionsBuilder<YourDbContext>();
        optionsBuilder.UseSqlServer("your connection string");

        return new YourDbContext(optionsBuilder.Options);
    }
}

You are using a new .net core EF which uses IHostBuilder.(in an older version like yours the provider is IWebHostBuilder).

The tools first try to obtain the service provider by invoking the Program.CreateHostBuilder(), calling Build(), then accessing the Services property.

You can learn more about Design-time DbContext Creation from Here

It may happen from a condition in your startup file or while you are injecting. for example, you have a flag that checks if some variable in appsettings is true to use inmemory database instance.

EF needs to build the model and use the DbContext without starting the application. When EF invokes methods, your config services are still null that's why you get an error.

Make sure you have installed the package

Microsoft.EntityFrameworkCore.Tools

By Shervin Ivari. Read the original answer on Stack Overflow.

There is a couple of ways to do it:

• If you reference the dll in Visual Studio right click it (in ProjectName/References folder) and select "Properties" you have "Version" and "Runtime Version" there.

• Alternatively, investigate it in code:

    Assembly assembly = Assembly.LoadFrom("TestAssembly.dll");
    Version ver = assembly.GetName().Version;
  

By PiotrWolkowski. Read the original answer on Stack Overflow.

If you know Class, that belongs to assembly, you can use GetTypeInfo

var runtimeVersion = typeof(MyClass)
.GetTypeInfo()
.Assembly
.GetCustomAttribute<AssemblyFileVersionAttribute>();

var version = runtimeVersion.Version;

The example is for .Net Core from https://developers.de/blogs/damir_dobric/archive/2017/06/27/how-to-deal-with-assembly-version-in-net-core.aspx

By Michael Freidgeim. Read the original answer on Stack Overflow.