Firebase Authentication returning specific user when app is uninstalled and Installed again

Question

I have an issue where I am using google sign in for my application + Firebase.

Suppose there are 3 users X,Y and Z with whom I am login in my application at one instance of time.

My code for checking the user is logged in or not:

FirebaseAuth mAuth = FirebaseAuth.getInstance();
FirebaseUser currentUser = mAuth.getCurrentUser();

if(currentUser!=null)
   {
     //user logged in and get user detail from currentUser and go to HomePage
   }
 else{
    //Show sign in button
   }

Scenario : I signed it with multiple accounts and logged out. everything working fine.

But when I delete the application and again install it. The Y user is automatically return by mAuth.getCurrentUser().

I tried login with X and Uninstall the application. Still, if I install it again it directly takes me to Y user.

I tried login with Z and Uninstall the application. Still, if I install it again it directly takes me to Y user.

I even tried login out and Delete the application. Again if I install, it returns Y user without even asking for sign in.

NOTE : I havent cleared cache or data . If I do that everything works fine.

The issue is just unistalling the app.

What must be the reason ?

_tried login with X and Uninstall the application_ where you able to login with X or was Y logged in? — Peter Haddad, Feb 07 '18 at 09:41
Again Y is returning. In whatever case if I uninstall the app and install it returns Y and I am really fumbled — Abubakker Moallim, Feb 07 '18 at 09:43
What about this `android:allowBackup="false"` in application tag — Sahdeep Singh, Feb 07 '18 at 09:51
Can you explain for what it is ? But I also know what to know the reason behind that Why only ``Y`` is returning — Abubakker Moallim, Feb 07 '18 at 09:53
Firebase keeps some data even after uninstalling, to delete data after uninstalling use these `android:allowBackup="false"` `android:fullBackupContent="false" ` . And i am not sure why only Y but you can try using this and after that test again by signing with X or Z without using these tags — Sahdeep Singh, Feb 07 '18 at 10:04

score 5 · Accepted Answer · edited Jun 20 '20 at 09:12

5

From the docs:

When a user signs up or signs in, that user becomes the current user of the Auth instance. The Firebase Auth instance persists the user's state, so that refreshing the page (in a browser) or restarting the application doesn't lose the user's information.

When the user signs out, the Auth instance stops keeping a reference to the User object and no longer persists its state; there is no current user. However, the user instance continues to be completely functional: if you keep a reference to it, you can still access and update the user's data.

So to solve this, the best way is to create a button and sign out the user. That way that user won't be logged in when you restart the application.

FirebaseAuth.getInstance().signOut();

More info here: https://firebase.google.com/docs/auth/users

Also this question related to ios (but same idea): Firebase - Deleting and reinstalling app does not un-authenticate a user

Some other alternatives also:

adding android:allowBackup="false" in your <application> in manifest.

android:allowBackup

Whether to allow the application to participate in the backup and restore infrastructure. If this attribute is set to false, no backup or restore of the application will ever be performed, even by a full-system backup that would otherwise cause all application data to be saved via adb. The default value of this attribute is true.

Do this as a Test:

Delete Cache and Data
Login with User Y and Logout
Login with User X and Logout
Uninstall the application
Install the application login with user X.

It is important to have FirebaseAuth.getInstance().signOut(); when logging out.

edited Jun 20 '20 at 09:12

Community

1
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answered Feb 07 '18 at 09:57

Peter Haddad

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_why only Y_ it seems you logged in with user Y from the beginning – Peter Haddad Feb 07 '18 at 09:58
But the thing is If I login with X and Delete app it should return X after installing – Abubakker Moallim Feb 07 '18 at 10:01
I am signing out on Logout but My questions is deleting the app . Even If I logout and delete the application and reinstall it. Still it returns Y – Abubakker Moallim Feb 07 '18 at 10:02
in the link about the ios, it says that even if you delete the app the data will stay there – Peter Haddad Feb 07 '18 at 10:03
Not the case. I logged out with Y uninstalled it . and reinstalling it still give Y – Abubakker Moallim Feb 07 '18 at 10:03
But My question is Why only ``Y`` everytime – Abubakker Moallim Feb 07 '18 at 10:04
1

@ABDevelopers who was the first user you logged in, in that application – Sahdeep Singh Feb 07 '18 at 10:05
try the test that I wrote in the answer – Peter Haddad Feb 07 '18 at 10:07
Let me check and revert you both @PeterHaddad Sahdeep Singh – Abubakker Moallim Feb 07 '18 at 10:11
android:allowBackup="false" solved the issue. But Still the question will be there about ``Y`` getting returned – Abubakker Moallim Feb 07 '18 at 10:19
what did the test return? – Peter Haddad Feb 07 '18 at 10:27
I tried the test as you said @PeterHaddad The ``currentUser`` is still returing ``Y`` . allowBackup=false solved the issue. But ``Y`` returning of Y always is still a mystery – Abubakker Moallim Feb 07 '18 at 10:28
delete user Y all together, from firebase console and any other place and see what you get then. It is probably something in your code, since if user is signing out then there should be no problem at all. In the test when u logged in with User X (before uninstall app), did it return user X or Y? Try in another phone also – Peter Haddad Feb 07 '18 at 10:43
I can delete Y because it is all the way having all my data. When I login with particular user it logins correctly. The issue was just unistall and install. – Abubakker Moallim Feb 07 '18 at 11:06
this should not be a problem even if u uninstall the app, I have done that many times while testing apps. If you are following the above answer and it is not working it is probably from the phone or from the code (maybe u had something and then changed it). If the answer helped, please also upvote it so it helps other people in the community, thank you! – Peter Haddad Feb 07 '18 at 11:56

Firebase Authentication returning specific user when app is uninstalled and Installed again

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