RequestServerSideAccess returns a null or empty authCode

[alandfranco]

Hi, I'm having trouble signing in to Unity services.

When I open the app, it logs in automatically with Google Play, and I can see my username, userId, etc.
However, when I try to link the authentication service of Unity with Google Play, it fails

I checked the SHA1 code, and it's correct. I tried another code, but it didn't work at all.
I have an OAuth 2.0 web client from which I took the client ID and client secret, and an Android client with the SHA1 code.

This is the code that should do everything.
`public async void SignIn()
{
PlayGamesPlatform.Activate();

if (PlayGamesPlatform.Instance.IsAuthenticated())
{
    await UnityServices.InitializeAsync();


    Debug.Log("Google Play already authenticated. Getting auth code for Unity...");            
    PlayGamesPlatform.Instance.RequestServerSideAccess(true, async authCode =>
    {
        if (string.IsNullOrEmpty(authCode))
        {
            Debug.LogError("Failed to retrieve auth code from Google Play.");
            return;
        }

        try
        {
            await UnityServices.InitializeAsync();

            if (!AuthenticationService.Instance.IsSignedIn)
            {
                await AuthenticationService.Instance.SignInWithGooglePlayGamesAsync(authCode);
                Debug.Log("Unity sign-in complete. PlayerID: " + AuthenticationService.Instance.PlayerId);
            }
            else
            {
                await AuthenticationService.Instance.LinkWithGooglePlayGamesAsync(authCode);
            }

            RaiseLoginEvent();
        }
        catch (Exception ex)
        {
            Debug.LogError("Unity sign-in failed: " + ex.Message);
        }
    });
}
else
{
    await Authenticate();
}

}

public async Task Authenticate()
{
await UnityServices.InitializeAsync();

PlayGamesPlatform.Activate();

PlayGamesPlatform.Instance.Authenticate((status) =>
{
    if (status == SignInStatus.Success)
    {
        string name = PlayGamesPlatform.Instance.GetUserDisplayName();
        string id = PlayGamesPlatform.Instance.GetUserId();
        string imgUrl = PlayGamesPlatform.Instance.GetUserImageUrl();

        Debug.Log("Google Play Games login successful: " + name);

        // Request auth code after new login
        
        PlayGamesPlatform.Instance.RequestServerSideAccess(true, async authCode =>
        {
            if (string.IsNullOrEmpty(authCode))
            {
                Debug.LogError("Auth code is null or empty. " + authCode);
            }
            else
            {
                Debug.Log($"Auth code received: {authCode}");
            }

            try
            {
                if (!AuthenticationService.Instance.IsSignedIn)
                {
                    await AuthenticationService.Instance.SignInWithGooglePlayGamesAsync(authCode);
                    
                    Debug.Log("Unity sign-in complete. PlayerID: " + AuthenticationService.Instance.PlayerId);
                }
                else
                {
                    await AuthenticationService.Instance.LinkWithGooglePlayGamesAsync(authCode);
                }

                RaiseLoginEvent();
            }
            catch (Exception ex)
            {
                Debug.LogError("Unity sign-in failed: " + ex.Message);
            }
        });
    }
    else
    {
        DetailsText.text = "Sign in Failed!!";
        Debug.LogError("Google Play Games login failed.");
    }
});

}`

I saw multiple tutorials, I have read all the documentation, and I cannot find what is wrong with my code or project configuration.

[jl-bourgot]

Hello,

I had the same issue using Plankton instead of this official SDK.

Try clearing your app’s cache — you should get the auth code again, but if you sign in once more, you won’t receive it a second time. According to the creator of Plankton, this is the normal flow as intended by Google. Personally, I gave up on integrating with Unity Authentication since it requires passing the auth code to its SignInAsync() method :

“That’s the expected behavior. The auth code is only returned on the first successful sign-in. You should send it to your backend server right away to exchange it for access and refresh tokens. The access token can be used to call Google APIs on behalf of the user, and the refresh token lets you get a new access token when needed. The auth code won’t be returned again on subsequent sign-ins unless the app’s data is cleared.”

The problem is that Unity’s documentation doesn’t mention any of this, and there’s no Refresh Token available (the mechanism is probably handled internally). I tried using SignOut(), etc., but nothing worked.

Maybe take a look at SignInAnonymouslyAsync(). According to their docs: “If a session token is cached on the SDK, then the SignInAnonymouslyAsync() method recovers the existing credentials of the cached player.”

My flow was like this :

• I call GameServices.SignIn() and wait for the auth code (equivalent to PlayGamesPlatform.Instance.RequestServerSideAccess).
• I pass the auth code to AuthenticationService.Instance.SignInWithGooglePlayGamesAsync() and await the AccessToken.
• I authenticate the client on my backend using Unity’s AccessToken, validating it via Unity’s JWKS.
• I then return my own AccessToken and RefreshToken to the client, valid for the current gameplay session.

[zeeshanvillaex1]

@jl-bourgot I am trying to access AccessToken via 'PlayGamesPlatform.Instance.RequestServerSideAccess" and I getting the error and sometime warning like that:
[Play Games Plugin 2.0] ERROR: Requesting server side access task failed - com.google.android.gms.common.api.ApiException: 10
What is the term 'GameServices.SignIn()' related to? It's not even a part of Unity Auth or Google Play games services. I've also tried to pass Unity's Access token in 'AuthenticationService.Instance.SignInWithGooglePlayGamesAsync()' but it gives error and that token gets generated via anonymous sign in. So yo're validating it via Unity's JWKS and passing it into 'AuthenticationService.Instance.SignInWithGooglePlayGamesAsync()'. I that working for you?

[manwithsteelnerves]

Here is some notes I have from our "Essential Kit for Unity Plugin" but this is valid for other plugins too.

1. If you are having trouble logging in, most likely your SHA fingerprint is wrong. Note for each environment(debug/release/play store) the SHA fingerprint changes and you need to add them as per your environment.
2. If you are sure your SHA is correct then cross check if your email is added in the testers list(in the Grow Users -> Play Game Services section - Check screenshot)
3. If you are sure about # 2 and you are accessing play services profile on your server, make sure the Server Client Id created is for Web Platform (Game Server) when creating the OAuth Credential.
4. If you are getting auth code as null, cross check once if the entered Server Client Id has any wrong characters or the value could be wrong or missing characters.
5. If you are able to access auth code first time only, make sure your fetch the refresh token too along with it. If you are using Essential Kit unity plugin, nothing to do as we do this by default. If you are on other plugins, make sure you pass true when requesting server side access for RefreshToken.

Note: Essential Kit for Unity doesn't use GPGS unity plugin internally, we have better control with our own custom implementations.

Cheers,
VB Team

[zeeshanvillaex1]

@manwithsteelnerves Well Thank you very much, I solved my issue by following this guide as I got my solution from Unity Discussion, and I followed this guide step by step:

https://discussions.unity.com/t/tutorial-authentication-with-google-play-games/911430
I found this guide very helpful and was able to access authcode.