How to Install LineageOS on OnePlus 3T with GApps

This is the minimal guide for installing LineageOS 17.1 on OnePlus 3T abtracted from LineageOS offical guide. It works at the time of writing so no gurantee for further updates.

  1. Enable OEM unlocking and USB debugging on your phone with developer mode.
  2. Download latest Android platform tools for Windows, for Linux, or for macOS from Google. The full guide can be found at Using ADB and fastboot.
  3. Connect your phone into your computer with USB mode.
  4. Install the built-in OnePlus USB Drivers or use UniversalAdbDriver.
  5. cd to the platform-tools directory, run adb devices to see if your phone is connected.
  6. Run adb reboot bootloader to boot your phone into bootloader mode.
  7. Run fastboot devices while in bootloader mode to see if your computer still connects to it.
  8. Run fastboot oem unlock. Your phone should be reset and reboot automatically.
  9. Setup your phone. Then re-enable USB debugging.
  10. Download latest custom recovery from TWRP.
  11. Run adb reboot bootloader to boot your phone into bootloader mode. Also make sure your phone can be find in fastboot mode by re-typing fastboot devices.
  12. Run fastboot flash twrp-3.4.0-0-oneplus3.img to flash custom recovery.
  13. Run fastboot boot twrp-3.4.0-0-oneplus3.img to boot into new recovery mode.
  14. Download the LineageOS installation package.
  15. Download Google Apps using the arm64 architecture. Choose the packages you prefer (I recommend nano package).
  16. In recovery mode, tap Swipe Format Data
  17. Return to the previous menu and tap Advanced Wipe, then select the Cache and System partitions and then Swipe to Wipe.
  18. Sideload the LineageOS and Google Apps packages:
    1. On your phone, tap AdvancedADB Sideload, then swipe to begin sideload
    2. On your computer, sideload the package using adb sideload
    3. Then sideload the Google Apps using adb sideload
  19. Back to recovery main menu. Reboot your device.
  20. Setup your LineageOS.