Fix App Lock Not Working in Bitdefender Mobile Security for Android

This guide helps you troubleshoot issues where App Lock is not working properly – or example, when it doesn’t prompt for a PIN/biometric, fails to lock apps randomly, or stops working after a while on certain apps or smartphones.

App Lock is designed to lock your Android apps with a PIN, so no one can access your private information or change device settings without your approval.

Follow the steps below to restore App Lock functionality.

1. Turn off Smart Unlock

App Lock includes a feature called Smart Unlock that skips PIN/biometric requests when your device is connected to a trusted Wi-Fi network. If App Lock appears to do nothing while you’re on a certain Wi-Fi, this may be the reason. This is normal behavior.

To disable Smart Unlock and force App Lock to ask for PIN every time:

1. Open Bitdefender Mobile Security.

2. Tap the More (∴) menu in the bottom-right corner and select Settings.

Settings

3. Scroll down to the App Lock section.

4. Tap Smart Unlock, turn it off, then tap OK.

Smart Unlock - App Lock not working Disable Smart Unlock

5. Additionally, if the preferred unlocking behavior indicates Lock after 30 seconds or Keep unlocked until screen off – tap it, select Require unlock every time and then tap OK.

Lock after 30 seconds or “Keep unlocked until screen off Require unlock every time - App Lock not working

6. Restart your phone.

Now open an app protected by App Lock to check if you’re prompted to enter your PIN or use biometrics. If the issue persists, continue with the next step.

2. Grant required Android permissions

App Lock relies on Android’s special app access: usage access to know the foreground app and overlay permission to show its unlock screen. Follow these steps to grant App Lock both permissions (Display over other apps and Usage access):

ⓘ The Android names/paths can vary slightly by phone model.

Display over other apps

Go to Android Settings ⚙︎ → Apps → Special app access

Apps Special app access

2. Tap on Display over other apps

Display over other apps - App Lock not working

3. Tap on Bitdefender Security → Allow.

Display over other apps > Bitdefender Security Allow - App Lock not working

This is the permission that lets Bitdefender show the PIN/biometric prompt above other apps.

Usage access

Go to Android Settings ⚙︎ → Apps → Special app access
Tap on Usage access → Bitdefender Security → Allow.

Usage access - App Lock not working Usage access > Bitdefender Security

This permission lets Bitdefender know which app is currently open so it can lock it when needed.

After enabling both permissions, test again by opening a locked app. If you are not prompted for the PIN/biometrics, move on to the next step.

3. Exclude Bitdefender from battery optimization

Aggressive battery optimizers on some phones can cause App Lock not working issues by stopping it from staying active. Exempt Bitdefender from battery optimizations to prevent the Android system from turning off App Lock in the background:

Go to Android Settings ⚙︎ → Battery (or Battery and device care) → Battery optimization / Background limits → set Bitdefender to Don’t optimize or Unrestricted.
Follow this vendor-specific guide (Samsung, Xiaomi/MIUI, Huawei/EMUI, OnePlus, etc.) if needed to exclude Bitdefender from battery optimization.

If you carefully go through the steps above – disabling Smart Unlock, granting the required permissions, adjusting battery settings – App Lock should lock your apps again.

Fix App Lock Not Working in Bitdefender Mobile Security for Android

1. Turn off Smart Unlock

2. Grant required Android permissions

3. Exclude Bitdefender from battery optimization

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