AuthError: Unexpected error occurred with message: Unsupported next step: completeAutoSignIn

[tmccaffrey914]

Describe the bug

During the "Sign Up" flow (so when creating a new user not authenticating an existing user) & after receiving and inputting the Email verification code - the authentication fails. In Cognito, I can see that the user was verified correctly & when you navigate back to the regular login screen and attempt to login - it's successful. Screen recording attached.

Before going into the steps to reproduce, I've tracked the issue down to this switch statement. When I run my signup flow the result is set to completeAutoSignIn with an associated Session Token. Since there is no case for completeAutoSignIn, program enters the default block which results in the error.

Screen Recording 2025-02-16 at 20.01.08.mov.zip

Steps To Reproduce

Steps to reproduce the behavior:
1. Set up a simple iOS app with only the Authenticator view:

    init() {
        do {
            try Amplify.add(plugin: AWSCognitoAuthPlugin())
            try Amplify.configure(with: .amplifyOutputs)
        } catch {
            print("Unable to configure Amplify \(error)")
        }
    }
    var body: some Scene {
        WindowGroup {
            Authenticator { state in
                RootView()
            }
        }
    }

2. Use the following `amplify_outputs.json`, no need for any amplify backend - I'm just using Cognito to generate session tokens to authenticate a different API Gateway.

{
  "version": "1",
  "auth": {
    "user_pool_id": "xxxxxxxxxxxxxx,
    "aws_region": "xxxxxxx",
    "user_pool_client_id": "xxxxxxxxxxxxx",
    "identity_pool_id": "xxxxxxxxxxxxxxxx",
    "mfa_methods": [],
    "standard_required_attributes": [
      "email"
    ],
    "username_attributes": [
      "email"
    ],
    "user_verification_types": [
      "email"
    ],
    "groups": [],
    "mfa_configuration": "NONE",
    "password_policy": {
      "min_length": 8,
      "require_lowercase": true,
      "require_numbers": true,
      "require_symbols": true,
      "require_uppercase": true
    },
    "unauthenticated_identities_enabled": true
  }
}

3. Here is my Cognito App Client configuration:

Identity Provider - Cognito User Pool
OAuth 2.0 Grant Type - Authorization Code Grant
OpenID Connect Scopes - Email, Phone, OpenID


Authentication flows:
Enabled: Choice-based sign-in: ALLOW_USER_AUTH
Enabled: Sign in with username and password: ALLOW_USER_PASSWORD_AUTH
Enabled: Sign in with secure remote password (SRP): ALLOW_USER_SRP_AUTH
Disabled: Sign in with server-side administrative credentials: ALLOW_ADMIN_USER_PASSWORD_AUTH
Disabled: Sign in with custom authentication flows from Lambda triggers: ALLOW_CUSTOM_AUTH
Enabled: Get new user tokens from existing authenticated sessions: ALLOW_REFRESH_TOKEN_AUTH

4. Try to "Sign Up" with a new user through the iOS simulator Login UI, after you enter the Email Verification code, a generic error appears on the screen and this error in the logs:
> AuthError: Unexpected error occurred with message: Unsupported next step: completeAutoSignIn("xxxxxxxxx-ThisWasASessionToken-xxxxxxxxxxx")
Recovery suggestion: This should not happen. There is a possibility that there is a bug if this error persists. Please take a look at https://github.com/aws-amplify/amplify-swift/issues to see if there are any existing issues that match your scenario, and file an issue with the details of the bug if there isn't.
5. Leave the "Sign Up" flow and go into the regular "Log In" flow and successfully log in with the new users details. Proving that the account was successfully added to the Userpool and successful Login is possible with the same credentials.

Expected behavior

The "Sign Up" flow should take you into the app the same way as would happen if you "Logged In"

Amplify Framework Version

2.45.4

Amplify Categories

Auth

Dependency manager

Swift PM

Swift version

5

CLI version

I uninstalled the CLI because I only need the Auth View

Xcode version

16.2 - 16C5032a

Relevant log output

<details>
<summary>Log Messages</summary>


AuthError: Unexpected error occurred with message: Unsupported next step: completeAutoSignIn("xxxxxxxxx-ThisWasASessionToken-xxxxxxxxxxx")
Recovery suggestion: This should not happen. There is a possibility that there is a bug if this error persists. Please take a look at https://github.com/aws-amplify/amplify-swift/issues to see if there are any existing issues that match your scenario, and file an issue with the details of the bug if there isn't.

</details>

Is this a regression?

No

Regression additional context

No response

Platforms

iOS

OS Version

iOS 18.2

Device

iPhone 16 Pro

Specific to simulators

No response

Additional context

No response

[github-actions]

This has been identified as a feature request. If this feature is important to you, we strongly encourage you to give a 👍 reaction on the request. This helps us prioritize new features most important to you. Thank you!

[thisisabhash]

Thank you for posting this. Currently, UI Authenticator doesn't have the auto sign in flow support. Our team will work on this and post updates here.

[tylerjroach]

@tmccaffrey914 Specifically, the unsupported auth flow on Authenticator is USER_AUTH. What authentication methods are you trying to support? If you are not using passwordless, you should be ok to get by with another auth flow type. https://docs.amplify.aws/swift/build-a-backend/auth/connect-your-frontend/switching-authentication-flows/

[tmccaffrey914]

Hi @tylerjroach , @thisisabhash - thanks for getting back to me so quickly. My only requirement is to be able to add federated auth, so Facebook/Google sign in - if I can do that without this auth type I’m happy to change to something else! Where would the USER_AUTH flag be set up so I can attempt to change it?

Edit:
Nevermind I think this must be it here:

Enabled: Choice-based sign-in: ALLOW_USER_AUTH

I’ll try disabling this flag tomorrow and see if that makes a difference.

[tmccaffrey914]

Hi team, disabling the ALLOW_USER_AUTH flag here:

Amazon Cognito > User pools > someuserpool-UserPool › App clients › App client: someappclient › Edit app client information

Allows me to login, so it's definitely caused by this flag. However, I think this needs to be enabled to support federated logins. So I suppose maybe this isn't a bug and just a feature request to support federated logins?

[tylerjroach]

@tmccaffrey914 Can you explain your use case a bit more?

Are you referring to the need to Federate to Cognito Identity Pool? It's not in the Authenticator, but you can use Amplify to federateToIdentityPool. This does not require ALLOW_USER_AUTH?

Authenticator does not support native social sign ins. Instead, you can launch social sign in's via our signInWithWebUI method: https://docs.amplify.aws/gen1/swift/build-a-backend/auth/add-social-provider/

If this still isn't what you are looking for, please provide more details on your specific use case.

[tmccaffrey914]

Hi @tylerjroach - no thats fine, I think this was just a misunderstanding on my side. Sign in using web ui method should be totally fine. Thanks for your help!