Web API Token Authentication throws exception No authentication handler is configured to handle the scheme: Microsoft.AspNet.Identity.Application - asp.net-mvc

Question

I have implemented Token Authentication for Web API using ASP.Net Core by following the solution mentioned in following post
Token Based Authentication in ASP.NET Core
To implement the authentication logic, I have defined following method
public async Task<bool> AuthenticateUser(string email, string password)
{
UserManager<ApplicationUser> _userManager = HttpContext.ApplicationServices.GetService(typeof(UserManager<ApplicationUser>)) as UserManager<ApplicationUser>;
SignInManager<ApplicationUser> _signInManager = HttpContext.ApplicationServices.GetService(typeof(SignInManager<ApplicationUser>)) as SignInManager<ApplicationUser>;
var result = await _signInManager.PasswordSignInAsync(email, password, isPersistent: false, lockoutOnFailure: false);
if (result.Succeeded)
{
return true;
}
else
{
return false;
}
}
and the Post method with is invoked is
[HttpPost]
public dynamic Post([FromBody] AuthRequest req)
{
string email = req.username;
string password = req.password;
try
{
bool isAuthenticated = false;
//implement the authentication logic over here
isAuthenticated = AuthenticateUser(email, password).Result;
if (isAuthenticated)
{
DateTime? expires = DateTime.UtcNow.AddDays(2);
var token = GetToken(req.username, expires);
return new { authenticated = true, entityId = 1, token = token, tokenExpires = expires };
}
}
catch (Exception ex)
{
return new { authenticated = false, message = "Exception: " + ex.Message, detailedmessage = ex.InnerException};
}
return new { authenticated = false };
}
Now the problem...
The Post executes fine on first call and returns the desired result, however, on second call, it throws following exception
No authentication handler is configured to handle the scheme: Microsoft.AspNet.Identity.Application
On debugging I found that this exception is being thrown when following line is executed
var result = await _signInManager.PasswordSignInAsync(email, password, isPersistent: false, lockoutOnFailure: false);
It works fine when invoked for the first time but throws exception on all subsequent calls.
I've been searching for this issue for the past 2 days and all I find is that in Startup.cs app.UseIdentity(); should be invoked before adding the authentication middleware. It's already happeneing in my code.
Please suggest what am I missing here.

Answer 1

Resolved the issue by changing HttpContext.ApplicationServices.GetService() to HttpContext.RequestServices.GetService() in AuthenticateUser() method. My updated method is
public async Task<bool> AuthenticateUser(string email, string password)
{
UserManager<ApplicationUser> _userManager = HttpContext.RequestServices.GetService(typeof(UserManager<ApplicationUser>)) as UserManager<ApplicationUser>;
SignInManager<ApplicationUser> _signInManager = HttpContext.RequestServices.GetService(typeof(SignInManager<ApplicationUser>)) as SignInManager<ApplicationUser>;
var result = await _signInManager.PasswordSignInAsync(email, password, isPersistent: false, lockoutOnFailure: false);
if (result.Succeeded)
{
return true;
}
else
{
return false;
}
}