How to Install GSI ROM on Pixel 3, 3 XL, 3a, & 3a XL!

In this tutorial, I show you how to install GSI ROM on Pixel 3, 3 XL, 3a, and 3a XL!

WARNING: PLEASE MAKE A BACKUP OF EVERYTHING BEFORE FOLLOWING THIS GUIDE as we will be DELETING EVERYTHING in order to install GSI ROMs!

Step 1. GSI ROMs are currently NOT compatible with Android 10 or 11 filesystem so if you want to install GSI ROMs like Havoc ROM, you will need to flash stock Android 9 first. Follow this tutorial here and install any Android 9 stock firmware:

Step 2. You will also need to unlock the bootloader, so please follow my universal guide on unlocking the bootloader if you haven’t yet:

Step 3. Download any “AB” GSI ROM. If this is your first time, I highly recommend you to try Havoc GSI ROM, download it here:

Download Havoc ROM Android 10 GSI:
https://download.highonandroid.com/file/GSI/Havoc/Havoc-OS-v3.8-20200821-Official-arm64-ab.img.zip.html

NOT ALL GSI ROMS boot and may not work with your phone but I have found Havoc ROM works with Pixel 3/3 XL/3a/3a XL so try this ROM first and then you can try other GSI ROMs. Also DO NOT DOWNLOAD w/ Gapps as you will end up in bootloop as we have to fix the system partition in TWRP before flashing Gapps to make it boot.

You can find other “AB” GSI ROMs on XDA here:

Step 4. You will also need fastboot.zip, TWRP recovery, and vbmeta.img:

Download fastboot.zip:
https://download.highonandroid.com/file/Tools/fastboot.zip.html

Download TWRP recovery for Pixel 3:
https://download.highonandroid.com/file/TWRP/Pixel3/twrp-3.3.0-0-blueline.img.html

Download TWRP recovery for Pixel 3 XL:
https://download.highonandroid.com/file/TWRP/Pixel3XL/twrp-3.3.0-0-crosshatch.img.html

Download TWRP recovery for Pixel 3a:
https://download.highonandroid.com/file/TWRP/Pixel3a/twrp-3.3.1-0-sargo.img.html

Download TWRP recovery for Pixel 3a XL:
https://download.highonandroid.com/file/TWRP/Pixel3aXL/twrp-3.3.1-0-bonito.img.html

Download vbmeta.img:
https://download.highonandroid.com/file/Tools/VBMeta/vbmeta.img.html

*Note - MAKE SURE YOU USE TWRP v3.3.0.0 or v3.3.1.0, newer versions are NOT GOING TO WORK as they don’t allow you to resize system partition!!!

For Windows users, also install ADB drivers:
https://download.highonandroid.com/file/Drivers/UniversalAdbDriverSetup.msi

Step 5. Unzip the GSI ROM so you get a file ending in “.img”. If you have downloaded another GSI and it’s in “.img.xz” format, use 7zip program to extra the “.img” file.

Also unzip fastboot.zip into “fastboot” folder in your “Downloads” directory.

Copy over the GSI “.img” file, TWRP image file, and vbmeta.img to the “fastboot” folder.

Step 6. Put your phone in fastboot mode by powering off and holding down Volume Down and Power buttons.

Then open a command prompt and type:

For Windows:

cd Downloads
cd fastboot
fastboot -w
fastboot reboot-bootloader
fastboot flash system PutNameOfGSIHere.img
fastboot reboot-bootloader
fastboot flash vbmeta vbmeta.img
fastboot reboot

For Linux:
cd Downloads
cd fastboot
chmod 755 *
sudo ./fastboot-linux -w
fastboot-linux reboot-bootloader
sudo ./fastboot-linux flash system PutNameOfGSIHere.img
fastboot-linux reboot-bootloader
sudo ./fastboot-linux flash vbmeta vbmeta.img
sudo ./fastboot-linux reboot

For Mac:
cd Downloads
cd fastboot
chmod 755 *
./fastboot-mac -w
./fastboot-mac reboot-bootloader
./fastboot-mac flash system PutNameOfGSIHere.img
./fastboot-mac reboot-bootloader
./fastboot-mac flash vbmeta vbmeta.img
./fastboot-mac reboot

Step 7. Your new ROM should boot but it’s missing Gapps or Google Play Store. Power off your phone then put it back into fastboot mode by holding down Volume Down + Power.

Then go back to command prompt and type:

For Windows:
fastboot boot PutNameOfTWRPHERE.img

For Linux:
sudo ./fastboot-linux boot PutNameOfTWRPHERE.img

For Mac:
./fastboot-mac boot PutNameOfTWRPHERE.img

Step 8. Once in TWRP, go into Wipe->Advanced Wipe, select “system” and choose “Repair”.

Once that’s done your system should have more space to install Gapps.

Step 9. Download latest Android 10.0 pico Gapps from here:
https://opengapps.org/

Step 10. Copy the Gapps zip file to your fastboot folder.

Step 11. Type in command prompt:

For Windows:
adb push NameOfGapps.zip /sdcard/.

For Linux:
sudo ./adb-linux push NameOfGapps.zip /sdcard/.

For Mac:
./adb-mac push NameOfGapps.zip /sdcard/.

Step 12. Install Gapps and reboot.

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