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I've an Android 9 Samsung tablet. I've set up normal (I.e. not limited) accounts for my children. When the tablet reboot, the only account which is usable is mine. The others are greyed out. When I've logged in once, the other accounts are unlocked.

I'd like my children to be able to use the tablet after a reboot without me needing to log in. How can I achieve that?

I found this question which seems similar but it has no answers.

user314888
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    I assume this is because of the device encryption (File Based Encryption). Before the main user has logged-in the device is not fully usable, therefore the other accounts are grayed-out. If my assumption is correct this is an integral property of Android and can't be changed. Keep in mind that Android is not a real multi-user OS. – Robert Feb 08 '20 at 11:57

2 Answers2

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It seems like by the primary user (here called "user 0") has to log in by definition as the first user. The documentation on the File Based Encryption (FBE) does not give many details on the question why:

Each user in a multi-user environment gets a separate encryption key. Every user gets two keys: a DE and a CE key. User 0 must log into the device first as it is a special user. This is pertinent for Device Administration uses.

Source: https://source.android.com/security/encryption/file-based#supporting-multiple-users

Hence I don't see a chance to change this behavior, you can only teach your children not to reboot the tablet and not to switch it off. In air plane mode with really disabled Wifi the battery loss should be minimal so that the tablet can stay on even when it is not used for some days.

Robert
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  • Disabling encryption indeed allows all users to log in immediately after a reboot. Well not something I recommend as permanent setting but it was nice to understand why it worked on my older tablet which had a version of Android without encryption. – user314888 Feb 10 '20 at 16:40
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    Is there a way to disable the FBE in android 12? It seems its there, turned on, but grayedout at least in Lenovo. – JCM Sep 02 '23 at 13:55
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Disabling FBE will get you what you want, though it seriously reduces the security of the device.

File Based Encryption (FBE) is called "Strong Protection" in the settings. On my tablet, you can disable it in Settings > Security > Other Security Settings > Strong Protection. (My tablet is a Samsung Galaxy running Android 11.) On some other devices it is under Biometrics And Security > Other Security settings.

I'm okay with disabling FBE, because the tablet is for my kids, who don't have much confidential information. But even in my case the tablet has all our Google passwords, because it's almost impossible to use an Android tablet without storing your Google password in a few apps.

(I deserve no credit for this answer, since it just combines information from comments. But I thought it would be nice to put the pieces together for someone who actually wants to change the setting.)

Dan R.
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