I have this MVC Application using a Discord OAuth2 Login to take username and ID. The problem is, no matter what I do, despite the URI PathString /signin-discord correctly directed to a method that returns a .cshtml view, it is instead always resulting in an “HTTP Error 500”.

I honestly have no idea what I did wrong that the URI isn’t properly returning the view.

Here is my configuration for Discord OAuth2 authentication:

   [HttpGet("/signin-discord")]
   public async Task<IActionResult> ExternalLoginCallback()
   {
       var authenticateResult = await HttpContext.AuthenticateAsync("Discord");

       if (!authenticateResult.Succeeded)
       {
           // Handle authentication failure
           return RedirectToAction("Login", "Account"); // Redirect to login page or handle as needed
       }

       // Retrieve Discord user information
       var userId = authenticateResult.Principal.FindFirst(ClaimTypes.NameIdentifier)?.Value;
       var username = authenticateResult.Principal.FindFirst(ClaimTypes.Name)?.Value;

       // Example: Authenticate user locally (store in session or database)
       var claims = new[]
       {
           new Claim(ClaimTypes.NameIdentifier, userId),
           new Claim(ClaimTypes.Name, username),
           // Add additional claims as needed
       };

       var identity = new ClaimsIdentity(claims, "Discord");
       var principal = new ClaimsPrincipal(identity);

       // Sign in the user
       await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, principal);

       // Redirect to your viewer page or any desired endpoint
       return View("DrawingPad"); // This will render Views/Drawing/DrawingPad.cshtml

       //return RedirectToAction("DrawingPad", "Drawing");

   }

I tried adjusting the Controller Method meant to be invoked by the URI, and setting its signature right at /signin-discord.

"   [HttpGet("/signin-discord")]public async Task<IActionResult> ExternalLoginCallback()//return RedirectToAction("Index", "Home");}

But nothing worked.