Install /e/ on a Teracube Teracube 2e (2021) - “emerald”

Tip: Please read through the instructions at least once before actually following them, so as to avoid any problems later.
Warning: Downgrading Smartphones already on Android Q or LineageOS 17.x to Pie or other OS can cause instability or at worst brick some devices
Caution: Flash your device only if you know what you are doing and are OK taking the associated risk. All builds are provided as best effort, without any guarantee. The /e/ project and its project members deny any and all responsibility about the consequences of using /e/ software and or /e/ services.


  • If required take a backup of all important data from your phone on an external storage device before proceeding.
  • Do not take a backup on the same device as some of these actions will format the device and delete the backup.
  • Ensure your phone is charged more than 50%
  • Check that adb and fastboot are enabled on your PC. If not you can find the setup instructions here
  • Download all the files and images mentioned in the download section below before starting the installation
  • Make sure you have a working data cable to connect your device to the PC. There are cables which are only for charging and do not transfer data.

  • Enable USB debugging on your device. You can find the instructions here
Caution: Do not install /e/OS on top of a higher version of stock OS. Before installing /e/OS ensure your device has the latest stock OS of the same version as /e/OS. If only lower versions of the stock are available then install the last available lower version before installing /e/OS.
Caution: Before moving forward, ensure your device is a Teracube 2e (2021). Please look at the serial number under the battery or dial *#06#. If the serial number starts with 2021 (ex: 202111T2Exxxxxx), you are at the right place! If it starts with 2020, please move to Teracube 2e (2020) documentation

Downloads for the emerald

To understand the difference between /e/OS builds check this guide

Warning: Please note some of the above links can lead to external sites

Unlock the bootloader

Caution: Please take a backup of your data as unlocking the bootloader will reset your device to factory defaults.
  • Enable USB debugging and Allow OEM Unlock following the guide given here
  • Reboot in fastboot

    • automatically: from your computer, run

      adb reboot bootloader


    • manually:

      Turn off your phone and start it with power + volume up keys.

      On the menu presenting three options, press volume up until fastboot is selected, and press volume down to accept this choice

  • OEM unlock the device

    Once your phone is in fastboot mode, on your PC type in a console the below command

    fastboot flashing unlock

    and press volume down on your phone to accept

  • The device will reboot automatically after an unlock.

Installing /e/ from the bootloader

  1. Download the build package linked in the Downloads section above and extract it to a folder of your choice
  2. Connect the device to your PC if not already done

    Ensure you have a cable which allowed file transfer. Some cables can only be used for charging.

  3. Move to the directory where you have extracted the files in the first step. To do that type the below command in a console
    cd path-of-the-extracted-files
  4. Install /e/OS by typing the following commands in the console
fastboot erase userdata
fastboot erase metadata

fastboot flash gz_a gz.img
fastboot flash lk_a lk.img
fastboot flash md1img_a md1img.img
fastboot flash scp_a scp.img
fastboot flash spmfw_a spmfw.img
fastboot flash sspm_a sspm.img
fastboot flash tee_a tee.img

fastboot flash boot_a boot.img
fastboot flash dtbo_a dtbo.img
fastboot flash vbmeta_a vbmeta.img
fastboot flash super super.img

fastboot --set-active=a
fastboot -w reboot
Tip: If your device is not detect by fastboot, try to use sudo fastboot instead
To find some troubleshooting tips… click here


  • Getting a Total xFer ':' 0.01x message - Try to upload the /e/OS to internal storage and retry to install
  • adb ':' sideload connection failed ':' insufficient permissions for device error - Try to execute the commands adb kill-server and adb start-server and retry
  • Running adb shell twrp install /sdcard/</e/ zip package> raise non-existent directory error - Try to check solution here
  • Getting an insufficient permissions error - Try the solution given here
  • When running "adb devices" in bash a device is shown as "unauthorized" - Try the solution given here


  • Errors while running TWRP version 3.4.x.x or above - Try downloading and using a previous TWRP version.. below 3.4.x.x
  • In TWRP if this error shows up failed to mount /preload - Try in TWRP wipe screen in advanced menu select preload and swipe to wipe
  • /cache/recovery/xxx -> no such file or directory error while flashing a ROM - On PC run adb shell in the console now create a folder called recovery for e.g. here the devicecode name is violet "violet :/cache# mkdir recovery"


  • Trying to troubleshoot mobile connectivity issues - Read this guide

Tip: To suggest changes to this install guide documentation, please visit the Teracube 2e (2021) specific topic on our community forum. To report issues in the build please refer this guide