Automating Authorization Code Flow. Unable to get session token

Questions
1

I was following the following thread Automating Authorization Code Flow , however, I’m not even able to get a session token.
We have a SPA application with the Authorization Code grant type and we have a test user that has a security question as MFA (MFA can’t be completely removed even for the test user).
When I’m trying to call api/v1/authn I get:

{
“errorCode”: “E0000004”,
“errorSummary”: “Authentication failed”,
“errorLink”: “E0000004”,
“errorId”: “oaeEzqyYkP4RA6tdj8b0pOb7w”,
“errorCauses”:
}

This Authentication | Okta Developer says that there are only 3 reasons for 401:

  • invalid credentials
  • locked out accounts
  • access denied by sign-on policy
    I am able to login with this user via UI so I don’t think it is an issue. The only difference is the security question but I haven’t found how to pass it (or if I need to) to get the session id.

Is there anything that I’m missing?

2

Can you log into Okta via the Okta login page with the same credentials you are using? User is a user within Okta (where their password is known in Okta), not Federated from an external IdP/integration, right?