Disable installation from unknown sources on Xiaomi Redmi Note 9: full instruction

Xiaomi Redmi Note 9 smartphones allow you to install applications not only from the official Google Play store, but also from third-party sources — so-called unknown sources. This feature can be useful for power users, but also opens the door to potential threats: viruses, spyware or unstable versions of applications.

By default, Redmi Note 9 (M2003J15SC, M2003J15SS and other modifications) installation from unknown sources is blocked globally, but users often accidentally allow it for individual applications (for example, browsers or file managers). In this article, we will discuss how to completely disable this option, return factory security settings and what to do if the menu item “unknown sources” disappears after the MIUI update.

Why it is important to disable the installation from unknown sources

The main danger of third-party APK-Files — no verification by Google Protect or Xiaomi's built-in scanner, and even if you downloaded a file from a trusted site, it could have been spoofed by malicious actors during the upload phase. Według Kaspersky statistics for 2023, more than 30% of malware for Android is distributed through manual installation APK, bypassing official shops.

Key risks:

• 🦠 Viruses and Trojans: Can steal bank card details, passwords or spy on users.
• 📱 Unstable System Performance: Unoptimized APK Often cause freezes or overheating of the processor.
• 🚫 Blocking Mi Account: if you detect suspicious activity, Xiaomi may temporarily block access to services.
• 🔄 Automatic Subscriptions: Some of the APK secretly connect paid services through SMS.

There are legitimate cases where the feature is needed, such as installing beta applications or enterprise software, but even in such cases it is better to use alternative methods (for example, ADB or Mi App Store with verified sources).

Where is the Unknown Sources setting in MIUI

Depending on the MIUI version (12, 13 or 14) and regional firmware (Global, EEA, Russia), the path to customization may vary. The Redmi Note 9 with MIUI 14 (Android 12) has the following routes:

The main path:

1. Open the settings (cog icon).
2. Go to the Appendix section → Application management.
3. Click on the three dots in the top right corner and select Special Access.
4. Slip on the item Installation from unknown sources.

Alternative path (for older versions of MIUI):

Settings → Additional → Privacy → Special Permits → Installation of Unknown Applications

If no item is available, it is possible:

• 🔍 You use enterprise firmware (for example, for business devices) where security settings are hidden.
• 🛠️ The phone has custom firmware (like LineageOS or Pixel Experience).
• 🔄 Failed after the update – you need to reset the settings (more about this below).

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If you can’t find an item on the menu, try searching by settings (the magnifier icon at the top of the screen) and enter the query “unknown sources”.

Step-by-step instruction for disconnection

To block APK installation from third-party sources, follow the following steps:

Step 1. Open the list of apps that are allowed to install APK. Here you will see all the programs that have ever requested this permission — for example, Chrome, Files or Telegram.

Step 2. For each application in the list, move the slider to the Off position..Please note: some system applications (e.g. com.android.packageinstaller) may not appear in this menu - this is normal.

Step 3. After disabling all items, try installing any APK-The system must give an error: "Installation is locked. To protect your phone, installing applications from unknown sources is prohibited».

If after these actions the installation still passes, check:

• 📌 Having superuser rights (Root) – they can bypass restrictions MIUI.
• 🔧 Developer settings (item Debugging by USB or allow installation through ADB).
• 🛡️ Antivirus programs (such as Avast or Dr.Web) that may have their own installation mechanisms.

Frequent Mistakes and How to Avoid Them

Many users have trouble disabling unknown sources, and the errors and solutions are:

Pay particular attention to applications that request permission to install APK implicitly. For example, some launchers or optimizers (like the DU Speed Booster) may disguise this request as “performance improvements.” Always read the full permission list when installing new software.

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If you're using the Redmi Note 9 Pro (the Joyeuse model), note that it can activate Dual Apps, which creates copies of apps with separate permissions. Check the settings for all clones!

Additional security measures

Disabling unknown sources is just the first step to protecting the device. For comprehensive security on the Redmi Note 9, we recommend:

1. Activate Google Play Protect: Go to Google Play → Menu → Play Protect and enable device scanning. This feature checks installed apps for threats in the background.
2. Install a reliable antivirus: Bitdefender or Kaspersky Mobile are well suited for MIUI – they integrate with system security settings.
3. Disable installation via ADB: In the developer settings (Settings → About Phone → MIUI version – tap 7 times) find Installation via USB and deactivate it.
4. Use Mi Account to lock: Link your device to your Xiaomi account and activate Find Device, which will allow you to remotely lock your phone when you steal.

For users who often work with APKs (such as testers or developers), the alternative is a sandbox, and applications like Shelter and Island allow you to isolate insecure programs from the main system without risking data.

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If you need to temporarily allow APK installation (for example, for work), use the guest mode in MIUI. Go to Settings → System → Guest mode and activate it. All changes to the guest profile will be reset after exit.

How to Disable Unknown Sources via ADB (For Power Users)

If standard methods don’t work (for example, due to custom firmware or corporate policies), you can use Android Debug Bridge (ADB), which requires connecting the phone to a computer and basic command line knowledge.

Instructions:

1. Download and install Google’s Platform Tools.
2. Activate Debugging via USB on your phone (in the developer settings).
3. Connect the Redmi Note 9 to your PC and enter:

adb devices


adb shell settings put global install_non_market_apps 0

To check your current status, use:

adb shell settings get global install_non_market_apps

If the command returns 0, the installation from unknown sources is blocked at the system level.

⚠️ Attention: Use ADB It can lead to disruptions in work. MIUI, If you type in the wrong commands, don't change other system parameters through the adb shell unless you're sure they're there. hidden_api_policy 1 It may disrupt some applications.

What to do if the settings reset after the MIUI update

After major updates (such as MIUI 12 to MIUI 14), some users notice that permissions for unknown sources are being reset to factory ones, which is because Xiaomi redistributes security rights whenever it changes the Android version.

Algorithm of action:

1. Check the firmware version: Go to Settings → About Phone → MIUI version. If version is below 14.0.5, upgrade the system.
2. Restore the settings manually: Repeat the steps from the step-by-step instructions above.
3. Reset the security center cache: Go to Settings → Applications → Application Management → Security Center and click Clear Cache.
4. Check system integrity: Enter ##4636## in the dialer and select Phone Information. MIUI Version should show the current build.

If the problem is repeated after each update, it may indicate that the partition /system is damaged, in which case only a complete flashing of the device through the Mi Flash Tool with the choice of the clean all option will help.

⚠️ Warning: Forced resetting of security settings via fastboot (fastboot erase userdata command) will delete all data on the phone, including photos and messages. → Additionally. → Backup and reset.

FAQ: Frequent questions