How to block the Xiaomi Mi9 bootloader: a step-by-step guide

Owners of the flagship devices of the Xiaomi series Mi9 They often think about digital security issues after buying or reselling a smartphone. PIN-The code or fingerprint protects only against surface access, but does not guarantee the safety of data in the event of deep interference with the system. If the device has previously been unlocked to install custom firmware, it remains vulnerable to an attacker who can reset the password through Recovery.

The Bootloader Factory Backloader is critical for anyone planning to sell a gadget or simply wanting to ensure the highest level of protection for personal information. Unlike simple menu settings, this operation requires interaction with Mi Unlock servers and adherence to strict time frames. Understanding the Bootloader security mechanism will help you avoid data loss and account lockdown.

In this guide, we will take a detailed look at the algorithm for locking the bootloader on the Mi9, how to properly prepare the device, what tools will be required and what to do in case of errors, and we will look at the nuances that are often overlooked when trying to simply reflash the phone in a standard way.

Why block the bootloader on Xiaomi Mi9

The bootloader is the first program to be launched when you turn on your smartphone, which initializes the launch of the operating system. When Bootloader is unlocked, anyone with physical access to the device can download custom Recovery and get full administrator rights (Root), which allows you to bypass the lock screen, copy photos, correspondence and passwords, even if the phone has a complex pattern lock.

Locking the bootloader returns the device to a “store-like” state. The system checks the digital signatures of all running components, preventing the launch of modified software. This is especially true for the Xiaomi Mi9, which supports fast charging methods and has powerful hardware that makes it an attractive target for data theft. A closed bootloader is also necessary for the correct operation of banking applications and Google Pay services, which often refuse to function on modified devices.

⚠️ Note: The lock procedure is only possible if the device is installed official global or Chinese firmware. Attempting to lock the bootloader on a custom build (for example, LineageOS or Pixel Experience) will lead to the inability to boot the system (bootloop).

In addition, a closed bootloader ensures the integrity of the update system.The smartphone will be able to automatically receive and install security patches from the manufacturer, which is critical to protect against new vulnerabilities.The open bootloader often breaks the chain of trust, and updates either do not come or require manual work through Recovery.

Necessary conditions and preparation of the device

Before you start manipulating system partitions, you need to perform a number of preparatory steps. Ignoring these steps can lead to the fact that the process will be blocked halfway, and the device will require a complex recovery procedure. First of all, make sure that the Xiaomi Mi9 smartphone has full logout from all accounts except the main Mi Account, which was used to unlock.

You will need a stable Internet connection, as the Mi Unlock Tool will conduct online verification of the status of the device on the company's servers. USB-A cable that can transmit data, not just charge the battery. Cheap charging-only cables often cause connection errors in Fastboot mode.

Make sure to back up all the important data. The process of locking the bootloader is 99% of the time accompanied by a complete reset of user data (Wipe Data). Even if you just reflash the device to close the bootloader, the internal memory will be cleared.

Check the current status of the bootloader. Turn off the phone and press the power and volume buttons at the same time. In Fastboot mode, you will see "Unlocked" with a picture of a rabbit fixing an android. If it says "Locked", then there is nothing to lock - your device is protected by default.

Tools for working with the loader

To successfully complete the task, you will need specialized software. The main tool is the Mi Unlock Tool utility, which can be downloaded exclusively from the official MIUI website. Using modified versions of this program from third-party forums carries the risk of malicious code or incorrect scripting.

Also, the computer must have ADB and Fastboot drivers installed. In Windows, this is often difficult, so it is recommended to use universal Google USB Driver drivers or specialized packages for Xiaomi. Without the right drivers, the Device Manager will not recognize the phone in bootloader mode, displaying it as "Unknown Device".

The table below shows the main components required for the procedure and their purpose:

Make sure your computer has an operating system that is not lower than Windows 7, although for Mi9 and modern versions of the utility it is better to use Windows 10 or 11. On macOS and Linux, work with Mi Unlock Tool is not officially supported and requires the use of emulators or virtual machines, which can introduce instability in the process.

The process of blocking through official firmware

The most reliable and safe way to lock the bootloader on the Xiaomi Mi9 is to flash the device with the official stable version of MIUI using Fastboot mode.This method is guaranteed to close the bootloader, since the firmware process includes a lock command at the end of the procedure.

To start, download the firmware archive specifically for Fastboot (it has the.tgz extension, not.zip). It is important to choose the version corresponding to the region of your device (Global, EU, Russia, to avoid problems with communication frequencies and NFC. After unpacking the archive, launch the file. flash_all_lock.bat from the tool folder if you use the command line, or select the corresponding option in the Mi Flash Tool GUI.

When using the Mi Flash Tool, select Clean all and lock mode, which automatically performs three actions: erase all user data, install a clean system, and send a command to close the bootloader. If you choose just "Clean all", the bootloader will remain open.

fastboot flashing lock


// or for older devices




fastboot oem lock

The phone will reboot several times during the firmware process. Don't interrupt the connection or press buttons on the device. The screen can go out and light up -- that's normal behavior when you rewire memory. The whole process takes 5 to 15 minutes depending on the speed. USB-port and data volume.

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Use it. USB-port soldered directly on the computer motherboard (back of the system unit). USB-Hubs may give insufficient power or unstable signal, which will lead to an error when writing the persist partition.

Blocking without flashing (only for certain cases)

There is a scenario where a user wants to close the bootloader but doesn’t want to reinstall the firmware, for example, if they just tested the Root rights and now want to return everything as it was, saving the data (although the data reset will still happen).Theoretically, the lock command can be sent directly through Fastboot, but on modern Xiaomi devices with anti-Rollback protection this does not always work linearly.

If you try to run fastboot oem lock on a device with modified system partitions, the phone can go into an endless reboot. Verified Boot will detect signature mismatch and refuse to boot. So the method of “clean” locking without firmware of the stock partition image and boot system is risky.

However, if you are sure that the system files are not modified, you can try the following method:

• 🔌 Connect your phone in Fastboot mode to your PC.
• 💻 Open the command line in the folder with ADB/Fastboot.
• 📝 Enter the command fastboot oem lock or fastboot flashing lock.
• 📱 On the phone screen will appear warning in English.
• ✅ Use volume buttons to select "Lock the bootloader" and confirm with the power button.

Once confirmed, the device will reset to the factory settings (Wipe Data) and restart. If the download was successful and you saw the welcome screen, the procedure is complete. If the phone is getting stuck on the Mi logo, then the system files have been changed, and you need a full flashing, described in the previous section.

⚠️ Note: On devices with the “Find Device” activated function, it is impossible to block the bootloader without first disabling this option in the Mi Account settings. Make sure that the function is deactivated before starting the procedure.

Possible mistakes and ways to solve them

Users often encounter a number of errors during bootloader locking, one of the most common being the “Couldn’t verify device,” which occurs when the Mi Unlock Tool entered is not the Mi Account that was used to unlock, or if the phone’s settings do not sign in to the same account.

Error: 10007 or similar codes often indicate problems with the network connection or servers of Xiaomi. DNS-servers on the 8.8.8.8 computer or use mobile internet via an access point, as providers sometimes block ports necessary to communicate with activation servers.

If the phone shows a black screen with the Fastboot logo or Mi logo after locking, but does not boot further, try to perform a forced reboot by holding the power button for 15-20 seconds. If this does not help, you will need to log in to Recovery mode and select the "Wipe Data" option, after which - "Reboot".

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The main key to success is the use of the original cable and stable Internet, as well as the exact correspondence of the firmware version to the region of the device.

Status check and final security

After successfully booting the system, it is recommended to conduct a final check. Go to Fastboot mode again, holding the power and volume buttons down. Now the label Locked should burn under the Fastboot logo, and the image of the hare with an open abdomen (the symbol of the open android) should disappear or change to a closed lock.

Also worth checking is security features. Try adding a fingerprint or setting up facial recognition. If these functions work correctly and do not give out errors about the compromised device, then the bootloader is successfully locked and the integrity of the system is not violated. Bank applications should also work without warning about risks.

Now your Xiaomi Mi9 is protected from unauthorized firmware reflashing. Even if the device falls into the wrong hands, an attacker will not be able to easily reset the password or steal data through a PC connection.