Xiaomi Mi 9 firmware: official and custom methods with unlocking the bootloader

The Xiaomi Mi 9, released in 2019, remains a popular smartphone among customization enthusiasts thanks to its powerful hardware (Snapdragon 855) and active community support. However, the firmware of this device has nuances, from the mandatory unlock of the bootloader to the features of working with the user. EDL-This article presents current firmware practices for 2026, including formal and informal solutions, given recent changes in Xiaomi policy (e.g., linking an account to a device when unlocking).

The Mi 9 firmware process (codenamed cepheus) depends on the goal: updating with MIUI Updater, installing global/European firmware instead of Chinese firmware, switching to custom firmware like LineageOS or Pixel Experience, or recovering from a crash. We will analyze all scenarios, paying attention to the critical points: checking the bootloader version (the Mi 9 has two V1 and V2), choosing the correct version of the Mi Flash Tool and bypassing the “Anti-Rollback” error. If you are a beginner, start with official methods; experienced users will need to use the sections about TWRP and Fast.

Preparation for firmware: what you need to know before you start

Before you start firmware, make sure your Xiaomi Mi 9 meets the key requirements. First, check the bootloader version: type ##4636## in the dialer, then go to Phone Information → bootloader Version. Mi 9 can have a V1 (old) or V2 (new, from 2020), which depends on the choice of firmware and tools.

Second, be sure to back up important data. Fastboot or Recovery firmware erases user files, and unlocking the bootloader resets the device to factory settings. Use Mi Mover, Google Photos for media files, and Titanium Backup for applications. Don't rely on the Mi Cloud cloud - after a reset, you may need to reauthorize.

• 📱 Device model: check in Settings → The phone. → Model, it must be. M1902F1G (global), M1902F1T (China) or M1902F1A (EEA).
• 🔋 Battery charge: at least 60%. The firmware can take up to 30 minutes, and discharging during the process will lead to a hard brick.
• 🖥️ Computer: Windows 10/11 (for the Mi Flash Tool or Linux/macOS (Macs may require additional drivers.
• 🔌 Cable: original USB Xiaomi's Type-C. Cheap cables often don't transmit data to Fastboot.

⚠️ Note: If your Mi 9 was purchased in China M1902F1T), Firmware of the global version through Fastboot without first unlocking the bootloader will lead to locking the device (Anti-Rollback 4.

Official firmware methods: MIUI Updater and Recovery

The safest way to upgrade the Mi 9 is to use the built-in MIUI tools. This method does not require unlocking the bootloader and is suitable for installing stable or beta versions of Xiaomi firmware. However, it has limitations: you can not downgrade the MIUI version or switch from Chinese firmware to global.

To update with MIUI Updater:

1. Open Settings → About the phone → System update.
2. Click on the three dots in the top right corner and select Select Service Pack.
3. Specify the path to the downloaded firmware file (.zip format, the name should contain) miui_cepheus).
4. Confirm the installation and wait for the reboot.

If the update is stuck on the MIUI logo for longer than 10 minutes, restart the device in Recovery (press Power + Volume Up) and select Wipe Data. This will solve the problem 90% of the time.

For installation via Recovery:

• 📁 Download the firmware from the official website (MIUI Downloads – Choose the version for cepheus.
• 📲 Rename the file to update.zip Put it in the root of your internal memory.
• 🔄 Reboot to Recovery and select Install update.zip.

Downgrade is only possible within one MIUI branch (for example, from 14.0.3 to 14.0.2).

Unlocking the bootloader: step-by-step instruction 2026

Without unlocking the bootloader, you can’t flash the Mi 9 through Fastboot or install custom Recovery.The process has changed since 2021: now you need to link your Mi Account to the device and wait 168 hours (7 days) after the first binding.

Instructions for unlocking:

1. Link your Mi Account to your device: Settings → Xiaomi Account → Sync.
2. Activate debugging via USB: Settings → About Phone → MIUI version (click 7 times), then Additional → For Developers → Debugging via USB.
3. Connect the phone to the PC and confirm the debugging permission.
4. Download Mi Unlock Tool (version no lower than 5.5.224.30).
5. Open the utility, log in to Mi and follow the instructions. If you see a message that says "Wait 168 hours," wait until the deadline expires.

⚠️ Note: Once the bootloader is unlocked, all data, including files in internal memory, will be reset. L1 (no HD into Netflix/Disney+), But it's fixable by reflashing the persist-section.

If the Mi Unlock Tool is a Couldn't unlock error:

• 🔌 Check the cable and port USB (Try the back port on the PC).
• 🖥️ Turn off the antivirus and firewall.
• 📱 Reboot your phone in Fastboot manually (Power) + Loudness down).
• 🔄 Try another version of the Mi Unlock Tool (e.g. 3.5.1118.45 for older devices).

Linking a Mi Account to a device|Enable debugging on USB|Install drivers ADB/Fastboot|Download the Mi Unlock Tool for the latest version|Prepare for 7-day-waiting-->

Fastboot firmware: official and custom

Fastboot is a versatile firmware method that allows you to install both official and custom firmware. For the Mi 9, it is critical to choose the right version of the Mi Flash Tool: any version is suitable for the V1 bootloader, and for V2 you need Mi Flash 2020.3.14.0 or later.

Instructions for official firmware:

1. Download the firmware for cepheus from the Xiaomi Firmware Updater website (choose the Fastboot version).
2. Unpack the archive in a folder without Cyrillic characters (for example, C:\Mi9_Fastboot).
3. Launch the Mi Flash Tool, press Select and specify the path to the firmware folder.
4. Connect your phone in Fastboot mode and press Refresh.
5. Select firmware method: Clean all (recommended); Clean all and lock (clean + lock) (official firmware only); Save user data (not always working).

Flash

For custom firmware (such as LineageOS or Pixel Experience):

1. Unlock the bootloader (see the previous section).
2. Install. TWRP for Mi 9 (version 3.7.0 Installation command: fastboot flash recovery twrp-3.7.0_cepheus.img fastboot boot twrp-3.7.0_cepheus.img
3. In TWRP, run Wipe → Format Data (required!), then copy the firmware to your phone and install it.

Error Solving: Anti-Rollback, EDL, and Other Problems

Xiaomi Mi 9 is known for two pitfalls: Anti-Rollback and EDL-Anti-Rollback is a rollback protection against the old firmware. If you try to install firmware older than the current one, the device will lock with the Anti-Rollback 4 error. The only solution is to flash the newer version through Fastboot or contact the service.

EDL (Emergency Download Mode) is a mode for recovering "brick" devices. To log into EDL on Mi 9:

1. Turn off the phone.
2. Press Volume Up + Volume Down and connect the USB cable to the PC.
3. Hold the buttons for 10-15 seconds until the Qualcomm HS-USB QDLoader 9008 port appears in Device Manager.

The recovery algorithm:

1. Try to log in to Fastboot (Food). + If you can, run the official firmware through the Mi Flash Tool with the Clean All option.
2. If Fastboot isn’t available, try EDL (see section above).This will require an authorized Xiaomi account or patched firmware.
3. As a last resort, use Test Point (closing contacts on the board for forced login to EDL). For Mi 9, the instruction is here.

⚠️ Note: If after the scoring of the EDL The phone is not switched on, but is defined as Qualcomm. HS-USB Diagnostics 900E, This means damage to the gpt partition. gpt.bin separately via QFil.

Frequent mistakes and decisions:

• 🔴 Remote: Partition Not Found: partition_table firmware.
• 🔴 FAILED (remote: 'Flashing is not allowed': bootloader locked.
• 🔴 Cyclical download after Xiaomi.eu: run Wipe Dalvik/Cache into TWRP.

FAQ: Answers to Frequent Questions