The “Authentication Failure 29” Error on Xiaomi Redmi Note 8 Pro: A Complete Remedy Guide

The Xiaomi Redmi Note 8 Pro is one of the brand’s most popular smartphones, but even it’s not immune to system bugs. One of the most frustrating problems owners face is the “Authentication Failure 29” (or Error 29) bug, which blocks access to the device after a bootloader is reset, firmware or attempted to unlock, most often due to a conflict with the Mi Account, a damaged firmware or incorrect actions when unlocking.

This bug doesn’t just prevent you from using your phone, it can completely block it, turning it into a brick. Unlike other system failures, the Error 29 requires a comprehensive approach, from checking your Xiaomi account to flashing it through Fastboot or EDL. In this article, we will discuss all working ways to solve the problem, including official and alternative methods, and also explain how to avoid re-emergence of the error.

What is the Authentication Failure 29 error?

Authentication Failure 29 is a code that appears on the Redmi Note 8 Pro screen when you try to:

• 🔄 reset to factory settings;
• 🔓 Unlock the bootloader through the Mi Unlock Tool;
• 📱 Switching the device through Fastboot or Recovery;
• 🔒 log in after a hard reset (Hard Reset).

The main reason is the conflict between Xiaomi’s hardware and software protection, which means that the phone authenticates the firmware and account data, but due to a failure it cannot confirm their legitimacy, most often in the following cases:

• 📵 Mi Account was tied to the device but not untied before resetting;
• 🔧 The firmware is damaged or incompatible with the bootloader version;
• 🔐 The bootloader is locked and the attempt to unlock is interrupted;
• 🛠️ The device was previously repaired with the replacement of the motherboard (modified) IMEI or S/N).

It's important to understand that Error 29 is not a hardware failure, but a software failure, which can be fixed without visiting a service center, but it will require access to a computer and special tools.

The reasons for the error on the Redmi Note 8 Pro

To effectively eliminate Authentication Failure 29, you need to understand its root.

Critical detail: On the Redmi Note 8 Pro, error 29 is often associated with the anti-rollback version of the bootloader. If you try to flash a version of MIUI older than the one originally installed, the phone will lock permanently. Check the current firmware version in the settings (Settings → Phone → MIUI version) before any manipulations.

⚠️ Warning: If you bought your phone with your hands and you don't know if it was tied to your Mi Account, never reset it to factory settings without detaching the previous owner's account. This is guaranteed to lead to an error of 29.

Official ways to correct the error

If your Redmi Note 8 Pro is locked with Authentication Failure 29 error, try the official solutions first.

1. Unleash Mi Account via Xiaomi website

If the error occurred due to an associated account, try untie the device remotely:

1. Go to the Mi Account website and log in.
2. In the Devices section, find your Redmi Note 8 Pro (by model or IMEI).
3. Click Remove the device and confirm the action.
4. Restart your phone and try to re-enter.

If the device is not listed or the Delete button is inactive, the account was not the main one on the phone, and you will need to contact the previous owner or use alternative methods.

2 Unlock the bootloader through the Mi Unlock Tool

If an error occurs when you try to unlock the bootloader, follow the procedure correctly:

Download Mi Unlock Tool from the official website|Sign in to Mi Account on your phone and tool|Connect your phone to your PC in Fastboot mode (clip Volume Down) + Nutrition)|Disable the antivirus on your PC (it can block the tool)-->

Next:

1. Launch the Mi Unlock Tool and log in to the same account as your phone.
2. Connect the Redmi Note 8 Pro in Fastboot mode.
3. Press Unlock and wait until it is completed (usually takes 3-5 minutes).
4. After unlocking, swipe your phone through the Mi Flash Tool with the Clean All tick.

⚠️ Note: If you unlock a message called Couldn't unlock or Device isn't bound to this account, it means that the account is not the same as the one that was originally linked to the phone.

3.Recovery via Mi Flash Tool

If the error occurred after a failed firmware, try to reflash the phone with the official firmware:

1. Download the latest stable firmware for Redmi Note 8 Pro (codename begonia) from MIUI Downloads.
2. Unpack the archive and copy the path to the folder with the firmware.
3. Install the Mi Flash Tool and run on behalf of the administrator.
4. Connect your phone in Fastboot mode (Loudness down + Power).
5. In Mi Flash Tool, select the firmware folder, select Clean All mode and press Flash.

If the firmware is successful, the phone will restart without error. If not, move on to alternative methods.

💡

The official methods only work when the Mi Account matches the unlocked bootloader. If the phone is bought from hand or the bootloader is locked, additional actions will be required.

Alternative solutions (for experienced users)

If the official methods don't work, you'll have to use more sophisticated methods, which require ADB skills, Fastboot skills, and sometimes you risk turning your phone into a brick if you do something wrong.

1. Unlocking through EDL (Emergency Download Mode)

EDL allows you to flash your phone at a low level, bypassing locks.

• 🖥️ Computer with Qualcomm drivers installed HS-USB QDLoader 9008;
• 📂.mbn firmware for Redmi Note 8 Pro;
• 🔧 Mi Flash Tool or QFil.

Instructions:

1. Turn off the phone.
2. Press Volume Up + Volume Down and connect the USB cable to the PC.The phone should be defined as a Qualcomm HS-USB QDLoader 9008.
3. Start the Mi Flash Tool, select the firmware and press Flash.
4. Wait until it is completed (it can take 10-15 minutes).

Important: The firmware over EDL erases all data, including Mi Account. If a phone has been stolen or locked by IMEI, this method may not work.

2. bypassing the error through TWRP and Magisk

If the bootloader is unlocked but error 29 remains, you can try:

1. Install custom Recovery (TWRP) via Fastboot:
2. In TWRP, reset Format Data (wipes everything, including internal memory).
3. Sweep Magisk to bypass the Mi Account verification:

This method doesn’t always work, but it sometimes helps to bypass account locking. Once you have Magisk firmware, the phone may boot up, but some features (like Google Pay) may not work.

3. Changing firmware files manually

For advanced users, there is a way to edit firmware files to fool the verification system.

• 📁 Unpacked firmware for Redmi Note 8 Pro;
• 🖥️ Hex editor (e.g. HxD);
• 🔧 Knowledge of file structure boot.img vendor.

The method is to delete or modify the files responsible for verifying Mi Account. However, this is risky: an incorrect change can lead to complete failure of the phone, XDA Developers or 4PDA).

Frequent errors in the elimination of Authentication Failure 29

Many users make the problem worse by making common mistakes, and this is what you can't do if you run into Error 29.

• 🚫 Use software to bypass Mi Accounts from dubious sites, most of which are virus-prone or not working.

Also not worth it:

• 💰 Paying unknown "masters" to unlock, often scammers who just search the phone in the standard way.

⚠️ Note: If you bought a Redmi Note 8 Pro with a 29 error and can’t fix it, check your phone for theft. IMEI If a device is blacklisted, it may not be possible to unlock it.

Prevention: How to avoid mistakes in the future

To avoid the Authentication Failure 29, follow these rules:

• 📱 Do not update your firmware through unofficial sources. use only the official Xiaomi website.

If you often experiment with firmware, keep on hand:

• 📄 Recording. IMEI and S/N (in case of restoration).

💡

Before buying used Xiaomi, always check whether the Mi Account is untied. Ask the seller to reset the settings with you. If after resetting the phone requires entering the username / password - refuse to buy.

FAQ: Answers to Frequent Questions