How To Guide [Magisk][US/CAN BL Unlock] Root for Galaxy S21 Series (B/N/0/U/U1/W)

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Nov 29, 2021
Hey bro any way of knowing when v4 would be able to be worked with like how long does a new bootloader version takes to be unlocked
I'm having issues with getting boot.img . I downloaded the SM-G9980 CSC TGY, used 7zip found AP, used 7zip in that, in there i found boot.img.lz4 and vendor_boot.img.lz4. I tried both files for magisk and it didnt work. Even tried removing the extension .lz4 but still installation failed. What can I do?

Edi: Figured it out, trying to figure out how to get into fast boot mode

May I ask what you did with the boot.img.LZ4 ? Neither WinRAR nor 7Zip recognize this as compressed format...


Senior Member
Jul 31, 2012


Nov 15, 2015
how can i unblock BL in europe? i cant see oem option in developer i tryed combinations with data but still doesnt help :(


Jan 16, 2022
So does anyone know if the devices currently shipping from Samsung still have the v1 bootloader and thus are worth getting?

I'm wondering if they're coming with newer bootloaders from the factory this late in the game.

Senior Member
May 14, 2015
OnePlus 9 Pro
Did anybody answer me if this model of European exynos can still be rooted on any bootloader? Due to the US killing off the 3G towers everyone's forced to have to buy a phone that's 5G compatible. If that wasn't the case I'd still have my note 9. I sadly have a OnePlus 9 pro now and I hate it!... Would love to buy this phone and root it if it's able to be rooted without having to be on a bootloader one or whatever. Thanks!


Jan 16, 2022
sorry, rev 3 on exynos G998B
rev 4 on G998U you still can go back
So I was able to find this tmobile 512gb model that has a 4 in the fifth position. Are you saying I can revert this back to version 1 so I can unlock the BL and then root it?


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    Note: this guide copied from topjohnwu's. Original guide here

    US/Canada bootloader unlock thread:

    Before Installing Magisk
    • Installing Magisk WILL trip KNOX
    • Unlocking bootloader for the first time will do a data wipe.

    If you already have Magisk installed, it is strongly recommended to upgrade directly via Magisk Manager using the “Direct Install” method. The following tutorial is only for initial installation.

    Getting Started

    Before you start:
    • This tutorial assumes you understand how to use adb and fastboot
    • If you plan to also install custom kernels, install it after Magisk
    • Your device’s bootloader has to be unlocked

    Download and install the latest Magisk app. In the home screen, you should see:


    The result of Ramdisk determines whether your device has ramdisk in the boot partition.

    Unlocking Bootloader

    Unlocking BL on modern Samsung devices have some caveats, so I figure this would be helpful.
    • Allow bootloader unlocking in Developer options → OEM unlocking
    • Reboot to download mode: power off your device and press the download mode key combo for your device (Vol Down + Vol Up) while connected to usb.
    • Long press volume up to unlock the bootloader. This will wipe your data and automatically reboot.

    If you think the bootloader is fully unlocked, it is actually not! Samsung introduced VaultKeeper, meaning the bootloader will still reject any unofficial partitions before VaultKeeper explicitly allows it.
    • Go through the initial setup. Skip through all the steps since data will be wiped again later when we are installing Magisk. Connect the device to Internet during the setup.
    • Enable developer options, and confirm that the OEM unlocking option exists and is grayed out. This means the VaultKeeper service has unleashed the bootloader.
    • Your bootloader now accepts unofficial images in download mode.

    Patching Boot Image

    If your device has boot ramdisk, you need a copy of the boot.img

    • Use either Frija or Samloader to download the latest firmware zip of your device directly from Samsung servers.
    • Unzip the boot.img from AP and copy the file to your device.
    • Press the Install button in the Magisk card
    • Choose “Select and Patch a File” in method, and select the stock boot image
    • Magisk Manager will patch the image to [Internal Storage]/Download/magisk_patched.img.
    • Copy the patched image to your PC
    • Flash the patched boot image to your device.
      For most devices, reboot into fastboot mode and flash with command:
      fastboot flash boot /path/to/magisk_patched.img or
      Rename magisk_patched.img to boot.img and use 7zip to make flashable tar of your boot.img
      Reboot to download mode. Open Odin on your PC, and flash boot_patched.tar as AP.
    • Reboot and voila!

    Patching AP

    • Use either Frija or Samloader to download the latest firmware zip of your device directly from Samsung servers.
    • Unzip the firmware and copy the AP tar file to your device. It is normally named as AP_[device_model_sw_ver].tar.md5
    • Press the Install button in the Magisk card
    • Choose “Select and Patch a File” in method, and select the AP tar file
    • Magisk Manager will patch the whole firmware file to [Internal Storage]/Download/magisk_patched.tar
    • Start the installation, and copy the patched tar file to your PC using ADB:
      adb pull /sdcard/Download/magisk_patched_[random_strings].tar
      DO NOT USE MTP as it is known to corrupt large files.
    • Reboot to download mode. Open Odin on your PC, and flash magisk_patched.tar as AP, together with BL, CP, and CSC (NOT HOME_CSC because we want to wipe data) from the original firmware.
    • Your device should reboot automatically once Odin finished flashing. Agree to do a factory reset if asked.
    • Install the Magisk app you’ve already downloaded and launch the app. It should show a dialog asking for additional setup.
    • Let the app do its job and automatically reboot the device. Voila!

    Custom Recovery​

    Installing using custom recoveries such as TWRP is only possible if your device has boot ramdisk.

    • Download the Magisk APK
    • Rename the .apk file extension to .zip, for example: Magisk-v2*.*.apk → Magisk-v2*.*.zip. If you have trouble renaming the file extension (like on Windows), use a file manager on Android or the one included in TWRP to rename the file.
    • Flash the zip just like any other ordinary flashable zip.
    • Reboot and check whether the Magisk app is installed. If it isn’t installed automatically, manually install the APK.

    @topjohnwu for magisk and guide, If you appreciate his effort, show some love and support :)

    The latest Magisk Canary release (21409) contains the fix needed for the S21 devices, yes (but being a Canary release there are of course other bugs).

    But, @afaneh92, since you're just copying @topjohnwu's installation instructions exactly, word for word, wouldn't it just have been easier to link to those instructions and let people know that Magisk Canary releases now can root the S21 Ultra (and maybe also warn people that the Canaries can be buggy)?
    US/Canada devices has no oem unlock toggle!
    Unlock service here

    How to get OEM Unlock option back for Non US/Canada device?
    1. Open the Settings app. Tap on General Management → Date and time.
    2. Use the toggle button to disable Automatic date and time.
    3. Set date option will be enabled now. Tap on it, and set the date to about 10-20 days earlier.
    4. Enable developer options.
    4.a Go to your device Settings.
    4.b Select ‘About phone’ » tap seven times on ‘Build number’.
    └ This will enable Developer options under Settings.
    4.c Go back to Settings » scroll down to the bottom and you’ll see Developer options menu.
    5. Open developer options (in the Settings app itself), and find the option called ‘Auto update system‘. Use the toggle button to disable it.
    6. Now, go back to the main screen of Setting, and then tap on Software update.
    7. Disable the option ‘Download updates automatically‘.
    8. Tap on ‘Download updates manually‘ option, but it will give you an error because of the wrong date, so it’s fine.
    9. Restart the device.
    10. Go to Settings > Developer options. The OEM unlock option should be enabled now.
    Thanks, but that doesn't apply to the S21 :coffee:
    Use latest magisk canary, I have rooted my S21 Ultra.
    I assume this will trip Knox right?
    Read the very first bullet, lol