Constructor with dependency injection causes http 500 error in react asp.net core app

The following controllers handle usage operations such as registration. However, when I Registeruse axios to call the method in the controller, I get the following error.

Failed to load resource: The server responded with a status of 500()

However, if I comment the code in the constructor, the call succeeds. I don't understand why the constructor produces this problem. Any suggestions?

public class ApplicationUserController : ControllerBase
{
    private IUserService _userService;
    private IMapper _mapper;
    private readonly AppSettings _appSettings;

    public ApplicationUserController(
        IUserService userService,
        IMapper mapper,
        IOptions<AppSettings> appSettings
    )
    {
        _userService = userService;
        _mapper = mapper;
        _appSettings = appSettings.Value;
    }

    [AllowAnonymous]
    [HttpPost]
    [Route("api/ApplicationUser/Register")]
    public IActionResult Register([FromBody]ApplicationUserDto userDto)
    { 
         //implementation details
    }
}

Here is the IUSerServices interface:

public interface IUserService
{
    ApplicationUser Authenticate(string username, string password);

}

public class UserService : IUserService
{
    private myDbContext _context;

    public UserService(myDbContext context)
    {
        _context = context;
    }

    public ApplicationUser Authenticate(string username, string password)
    {
        //implementation details
    }
}

DI is registered atStartup.cs

services.AddScoped<IUserService, UserService>();
services.AddScoped<myDbContext>();