Install LineageOS on
Xiaomi 12S Ultra

Basic requirements

1. Read through the instructions at least once before actually following them, so as to avoid any problems due to any missed steps!
2. Make sure your computer has adb and fastboot. Setup instructions can be found here.
3. Enable USB debugging on your device.
4. Make sure that your model is actually listed in the “Supported models” section here (exact match required!)
5. Boot your device with the stock OS at least once and check every functionality.
   warning

   Warning: Make sure that you can send and receive SMS and place and receive calls (also via WiFi and LTE, if available), otherwise it won’t work on LineageOS either! Additionally, some devices require that VoLTE/VoWiFi be utilized once on stock to provision IMS.
6. LineageOS is provided as-is with no warranty. While we attempt to verify everything works you are installing this at your own risk!

Checking the correct firmware

Installation on your device requires a specific firmware version to be installed before you continue.

• Firmware refers to a device-specific set of images that are included in, and updated by the stock OS
• LineageOS builds for this device require an Android 14 version of the stock OS to be installed prior to following the installation guide
• Please ensure that you are checking the Android version, and not the vendor OS version
• Being on another custom ROM, including unofficial builds of the same version of LineageOS, does not ensure that this requirement has been fulfilled
• Please re-read this section as many times as necessary to fully understand the requirements

Failing to install the correct firmware version prior to installation may result in failure to install LineageOS, unexpected crashes post-installation, or permanent damage to your device!

Unlocking the bootloader

1. Create a Mi account on Xiaomi’s website. Beware that one account is only allowed to unlock one unique device every 30 days.
2. Add a phone number to your Mi account.
3. Insert a SIM into your phone.
4. Enable developer options in Settings > About Phone by repeatedly tapping MIUI Version.
5. Link the device to your Mi account in Settings > Additional settings > Developer options > Mi Unlock status.
6. Download the Mi Unlock app (Windows is required to run the app).
7. Run the Mi Unlock app and follow the instructions provided by the app. It may tell you that you have to wait up to 30 days. If it does so, please wait the quoted amount of time before continuing to the next step!
8. After device and Mi account are successfully verified, the bootloader should be unlocked.
9. Since the device resets completely, you will need to re-enable USB debugging to continue.

Flashing additional partitions

1. Download the following files from here.
   • boot.img
   • dtbo.img
   • vendor_boot.img
2. Power off the device, and boot it into bootloader mode:
   • With the device powered off, hold Volume Down + Power. Keep holding both buttons until the word “FASTBOOT” appears on the screen, then release.
3. Flash the downloaded image files to your device by typing:

   fastboot flash boot boot.img
   fastboot flash dtbo dtbo.img
   fastboot flash vendor_boot vendor_boot.img
   

Installing Lineage Recovery using fastboot

1. Download Lineage Recovery. Simply download the latest recovery file, named recovery.img.
   warning

   Important: Other recoveries may not work for installation or updates. We strongly recommend to use the one linked above!
2. Connect your device to your PC via USB if it isn’t already.
3. If your device isn’t already in fastboot mode, on the computer, open a command prompt (on Windows) or terminal (on Linux or macOS) window, and type:

   adb -d reboot bootloader
   

   You can also boot into fastboot mode via a key combination:

   • With the device powered off, hold Volume Down + Power. Keep holding both buttons until the word “FASTBOOT” appears on the screen, then release.
4. Once the device is in fastboot mode, verify your PC finds it by typing:

   fastboot devices
   

   If you don’t get any output or an error:

   • on Windows: make sure the device appears in the device manager without a triangle. Try other drivers until the command above works!
   • on Linux or macOS: If you see no permissions fastboot try running fastboot as root. When the output is empty, check your USB cable (preferably use a USB Type-A 2.0 one or a USB hub) and port!
   check

   Tip: Some devices have buggy USB support while in bootloader mode, if you see fastboot hanging with no output when using commands such as fastboot getvar ..., fastboot boot ..., fastboot flash ... you may want to try a different USB port (preferably a USB Type-A 2.0 one) or a USB hub.
5. Flash recovery onto your device:

   fastboot flash recovery recovery.img
   

6. Now reboot into recovery to verify the installation. Do not reboot into the existing OS, since it will overwrite the recovery you just installed!

   • With the device powered off, hold Volume Up + Power. Keep holding both buttons until the “MI” logo appears on the screen, then release.

     info_outline

     Note: If you can’t power down the device, try long-pressing the key-combination (if any was used in the instructions above) until the device reboots and follow the instructions above
   info_outline

   Note: If your recovery does not show the LineageOS logo , you accidentally booted into the wrong recovery. Please start at the top of this section!

Installing LineageOS from recovery

1. Download the LineageOS zip file that you would like to install or build the package yourself.
2. If you are not in recovery, reboot into recovery:
   • With the device powered off, hold Volume Up + Power. Keep holding both buttons until the “MI” logo appears on the screen, then release.
3. Now tap Factory Reset, then Format data / factory reset and continue with the formatting process. This will remove encryption and delete all files stored in the internal storage, as well as format your cache partition (if you have one).
4. Return to the main menu.
5. Sideload the LineageOS .zip package but do not reboot before you read/followed the rest of the instructions!
   • On the device, select “Apply Update”, then “Apply from ADB” to begin sideload.
   • On the host machine, sideload the package using: adb -d sideload filename.zip.
     check

     Tip: After the package is installed, recovery will inform you that reboot to recovery is required to install add-ons. In case you want to do that, please select “Yes,” otherwise “No”.
     check

     Tip: Normally, adb will report Total xfer: 1.00x, but in some cases, even if the process succeeds the output will stop at 47% and report adb: failed to read command: Success. In some cases it will report adb: failed to read command: No error or adb: failed to read command: Undefined error: 0 which is also fine.

Installing Add-Ons

1. Click Apply Update, then Apply from ADB, then adb -d sideload filename.zip for all desired packages in sequence.
   When presented with a screen that says Signature verification failed, click Yes. It is expected as add-ons aren’t signed with LineageOS’s official key!

All set!

Once you have installed everything successfully, you can now reboot your device into the OS for the first time!

• Click the back arrow in the top left of the screen, then “Reboot system now”.