ARB in Xiaomi: what it is, how it works and why it is important for firmware

If you've ever tried to flash a Xiaomi device (especially a TV or a smartphone on Qualcomm), you've probably come across the term ARB, Anti-Rollback Protection. It's a security system that blocks rollbacks on older versions of firmware and prevents unofficial software from being installed. But why is it so important, and how do you work with it? Let's get to the bottom of it.

ARB has emerged as a response to a common problem: users have often tried to downgrade firmware (install an older version), which has led to device failures. In Xiaomi’s case, this technology is especially relevant for PatchWall TVs (such as Mi TV 4A/4S/4X), as well as for smartphones on Snapdragon chipsets. If ARB is not included, the device can turn into a “brick” – a completely inoperable device.

In this article, we will explain in detail what ARB is, how it works on different Xiaomi devices, and what to do if you encounter errors such as anti-rollback check fail or EDL mode required.

What is ARB (Anti-Rollback Protection) in Xiaomi?

ARB (Anti-Rollback Protection) is a security mechanism that prevents installing firmware older than the one already installed on the device, and its main goal is to prevent system instability due to component incompatibility. For example, if you upgrade your Xiaomi Mi TV 4S to PatchWall 3.0 and then try to return to PatchWall 2.5, ARB will block this process.

Why does this matter? Because newer versions of firmware are often optimized for updated drivers and libraries, a rollback to the older version can lead to:

• 🔴 Loss of functionality – some modules (such as Wi-Fi or Bluetooth) may stop working.
• 🔴 Security vulnerabilities – older versions of software often contain unpatched bugs.
• 🔴 "Brick device – in the worst case, the TV or smartphone will stop turning on.

ARB is implemented at the bootloader level and is controlled via special flags in the aboot section (for devices on Qualcomm) or in uboot (for TVs on Amlogic). If the firmware does not pass the ARB check, the device goes into EDL (Emergency Download Mode) mode, an emergency boot mode from which it is impossible to exit without special tools.

Which Xiaomi devices have ARBs on?

Anti-Rollback technology is not used on all Xiaomi gadgets, but is especially relevant for devices with a closed bootloader and strict firmware control.

A particularly rigorous ARB check is implemented in Xiaomi TVs, for example, if you try to flash the Mi TV 4S 55 firmware from the Mi TV 4A, even if they are on the same chipset, the ARB will block the process due to a mismatch of anti-version, a special numerical identifier that increases with each new firmware.

On smartphones, ARB is most often manifested when trying to install custom software (for example, LineageOS) without first unlocking the bootloader through the official Mi Unlock Tool. In this case, the device can go into the EDL-mode, and it will require an authorized Xiaomi account or a special box (for example, UFi Box or EasyJTAG).

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Before you run your firmware, always check the ARB version in aboot.img (for smartphones) or in the uboot (for TVs) section, and this can be done with tools like the Mi Flash Tool or Hex editor.

How to find out the ARB version on your Xiaomi device?

To avoid firmware problems, you need to know the current version of Anti-Rollback on your device.

For Xiaomi TVs (Mi TV, Redmi TV):

1. Go to Settings → About TV → PatchWall version.

2. Write down the current version (e.g. PatchWall 3.0.123).

3. Compare it to the firmware version you're going to install. If the new firmware is older, it won't be a problem. If it's younger, ARB will block the installation.

For Xiaomi smartphones (Redmi, POCO, Mi):

1. Install the Mi Check Tool app (available on 4PDA or XDA Developers).

2. Connect your phone to your PC and run the command in ADB:

adb shell getprop ro.boot.anti_version

3. In the answer you will see a number (e.g. 3 or 5) – this is the current version of ARB.

Also version ARB You can find it in your firmware files. For example, in your TV software archive, open the file. update.zip and check the line anti_rollback_version file-wise upgrade_config. If this number is less than on your device, the firmware will not install.

ARB Errors: What to do if the firmware is blocked?

If you see a message like anti-rollback check fail or device is locked, it means that the firmware has not passed the ARB test. Depending on the device, there are several ways to solve the problem:

For Xiaomi TVs:

• 🔧 Install a newer firmware – download the latest official version from Xiaomi’s website and run through it. USB OTG.
• 🔧 Use an Authorized File – Some Firmware for Mi TV require authorization through Xiaomi account (you need a Mi Account with a connection to the device).
• 🔧 Contact the service center if the TV is gone EDL, Self-recovery may not be possible without special equipment.

For Xiaomi smartphones:

• 📱 Unlock the bootloader via Mi Unlock Tool (requires account binding and waiting) 7-15 days).
• 📱 Scroll through Fastboot with the correct version ARB — use the command:

fastboot flash aboot aboot.img


fastboot flash boot boot.img




fastboot reboot

Where aboot.img and boot.img are files from firmware with an ARB version not lower than the current one.

Check the current version ARB through ADB|Download the firmware with the version ARB below the current|Unlock the bootloader (if not unlocked)|Use the Mi Flash Tool in "clean all" mode"|Don't interrupt the firmware process-->

Important: if the device has gone into EDL-Mod after a failed firmware, self-recovery without an authorized Xiaomi account or boxing (UFi, EasyJTAG) is almost impossible.

⚠️ Attention: Attempting to get around ARB on Xiaomi TVs using unofficial firmware (for example, ATV or CoreELEC) can cause warranty loss and irreversible damage to the bootloader.Firmware from third-party developers often fails anti-version testing.

Can you bypass ARB on Xiaomi?

It is technically possible to bypass Anti-Rollback Protection, but it requires deep knowledge and often leads to a loss of warranty.

1. Change of anti-version in firmware

Some users edit aboot.img (for smartphones) or uboot (for TVs) with a Hex editor, zooming in the ARB version to the right one, but this only works if:

• ✅ You have a backup of the original bootloader.
• ✅ You know exactly which bytes to change (usually offset) 0x1000 booty).
• ✅ The device does not verify the digital signature of the bootloader (on new models this is blocked).

2.Use of EDL-fashion-authorization

For devices on Qualcomm (most Xiaomi smartphones), you can log into EDL and flash a modified aboot with a zeroed-out version of ARB.

• 🔑 Authorized Xiaomi Account (for new devices).
• 🔑 Special Boxing (UFi Box, EasyJTAG) or QFil Patched Box.
• 🔑 Knowledge of commands for firehose firmware.

On Xiaomi TVs bypass ARB It is even more complicated – often a soldering station is required to connect to the UART hand-stitching NAND-memory.

⚠️ Attention: Bypass ARB on devices with MediaTek (e.g. Redmi Note) 8T or Mi TV 4A on MTK) It is almost impossible without official access to DA-Attempts to use informal methods often result in complete data loss.

ARB and custom firmware: are they compatible?

If you plan to install custom firmware (like LineageOS, Pixel Experience or Havoc OS) on a Xiaomi device, ARB can be a major hurdle.

• 📌 For smartphones: Most custom firmware requires an unlocked bootloader and a compatible version ARB. Before installation, check on the forum XDA Developers or 4PDA, Does the firmware support your model and anti-version version.
• 📺 For TVs: Castom firmware like CoreELEC or ATV often ignored ARB, But installing them may result in the loss of PatchWall features (for example, the remote and some applications will not work).
• 🔧 General advice: If you are a beginner, it is better to stay on official software or use firmware with confirmed support. ARB (for example, MIUI EU smartphone).

Example: on POCO F1 (beryllium), custom firmware usually works without ARB problems, as long as the anti-version version is no lower than in stock firmware. On Redmi Note 7 (lavender), a patch for aboot may be required when installing LineageOS 18.1.

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Castom firmware does not always take into account ARB. Before installing, check on the forums whether the selected firmware is compatible with your version of anti-version. Otherwise, you risk getting a brick.

Frequent questions about ARB in Xiaomi (FAQ)