«This phone is not supported.» (Android 14 and hardware keys)

Symptom

When opening the approver app, you see «This phone is not supported. Phone approval needs Android 14 or later with hardware-backed key storage.» and you cannot link accounts.

Cause

Phone approval keeps the approval key in a secure chip on the phone, which it never leaves. That needs:

• Android 14 or later;
• hardware-backed key storage (StrongBox, or the processor's secure environment);
• a system that can prove this protection (key attestation).

Older phones, phones without a secure chip, or phones with a modified system do not meet these requirements.

Fix

1. Check the Android version under Settings › About phone. If an update to Android 14 or later is available, install it.
2. If the phone cannot be updated, use another compatible Android phone.
3. Meanwhile, sign in with a passkey on the computer or a security key. See Create a passkey.

What if I have an iPhone?

There is no approver app for iPhone yet. Use a passkey: the iPhone stores passkeys and can use them to sign in on the computer. See What is not supported yet.

When to escalate

If the phone meets the requirements and the message persists, contact your helpdesk with the model and Android version.