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

[afaneh92]

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

US/Canada bootloader unlock thread:
here

Before Installing Magisk

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

Installation

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

Instructions

• 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

Instructions

• 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.

Instructions

• 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.

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

Donations
https://www.patreon.com/topjohnwu
https://www.paypal.me/topjohnwu

 

[afaneh92]

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.

 

[Amir majadly]

Thank You very much for your awesome work!!

 

[Boomorrow]

Thanks, but that doesn't apply to the S21

 

[afaneh92]

Thanks, but that doesn't apply to the S21

Use latest magisk canary, I have rooted my S21 Ultra.

 

[Didgeridoohan]

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)?

 

[OneFloofySheep]

Thanks for this amazing valentines gift

 

[bhammler]

thanks - its working

 

[iloveco]

Does this work on all S21+ Ultra variants?

 

[afaneh92]

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)?

Its not just a copy and paste! I have edited the the guide to suit our S21 series.

 

[Didgeridoohan]

Its not just a copy and paste! I have edited the the guide to suit our S21 series.

Edited?

These few lines are the only things that do not exactly match John's instructions:

• Unzip the boot.img from AP and copy the file to your device.
• <Copy of John's flashing boot image instructions>
• 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.

99% of that 1st post is a copy-paste... You should know the rules on this forum. Copying others work, even text, without proper credits is a no-no.

And no: a small "thanks for the guide" isn't proper credits. Be transparent with where you copy stuff from.

 

[afaneh92]

Edited?

These few lines are the only things that do not exactly match John's instructions:

• Unzip the boot.img from AP and copy the file to your device.
• <Copy of John's flashing boot image instructions>
• 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.

99% of that 1st post is a copy-paste... You should know the rules on this forum. Copying others work, even text, without proper credits is a no-no.

And no: a small "thanks for the guide" isn't proper credits. Be transparent with where you copy stuff from.

Also removed unnecessary instructions!
Thanks for clarification, I will add link to topjohnwu guide and donations

 

[chenjingyuan98]

Work hard and I succeeded. Thanks again to the author

Mod Edit : English only !

Google translation :

Work hard and I succeeded. Thanks again to the author,

 

[NuLuumo]

I recently got a Samsung S21 Ultra 5G from Verizon. I live in the US, and I have read online that the US variants are more difficult to root. The model is SM-G998U, with Snapdragon.

The serial number is R3CR106XBXT, if that helps at all.

The main issue I've been facing is unlocking the bootloader -- it doesn't seem to show up in the Developer Options menu, unfortunately. I am able to enter recovery mode but selecting the option to boot into the bootloader only restarts the phone.

I am able to use ADB in the command prompt, as it detects the phone fine when checking 'adb devices'.

I have tried doing 'adb reboot bootloader' but it only does the same as trying it from recovery mode.

The only other 'mode' that works is Samsung's Download mode' which I think only works with Odin.

Trying 'fastboot devices' during this screen yields no results.

Am I out of luck for trying to get this device rooted?

Thank you!

 

[Burt Squirtz]

I recently got a Samsung S21 Ultra 5G from Verizon. I live in the US, and I have read online that the US variants are more difficult to root. The model is SM-G998U, with Snapdragon.

The serial number is R3CR106XBXT, if that helps at all.

The main issue I've been facing is unlocking the bootloader -- it doesn't seem to show up in the Developer Options menu, unfortunately. I am able to enter recovery mode but selecting the option to boot into the bootloader only restarts the phone.

I am able to use ADB in the command prompt, as it detects the phone fine when checking 'adb devices'.

I have tried doing 'adb reboot bootloader' but it only does the same as trying it from recovery mode.

The only other 'mode' that works is Samsung's Download mode' which I think only works with Odin.

Trying 'fastboot devices' during this screen yields no results.

Am I out of luck for trying to get this device rooted?

Thank you!

this is exactly what I'm encountering as well. I have the US unlocked version of the s21 ultra. Incredibly annoying - as there's no OEM unlocking option under Dev options. I tried the 'set the date back 7 Days' trick that supposedly makes work. It does absolutely nothing.

I'm dangerously close to returning this phone and going back to my OnePlus 8 pro which was overall much better experience. The 8 pro had way better touch response, much more beautiful screen, and was completely rootable and able to have ROMs.

 

[afaneh92]

I recently got a Samsung S21 Ultra 5G from Verizon. I live in the US, and I have read online that the US variants are more difficult to root. The model is SM-G998U, with Snapdragon.

The serial number is R3CR106XBXT, if that helps at all.

The main issue I've been facing is unlocking the bootloader -- it doesn't seem to show up in the Developer Options menu, unfortunately. I am able to enter recovery mode but selecting the option to boot into the bootloader only restarts the phone.

I am able to use ADB in the command prompt, as it detects the phone fine when checking 'adb devices'.

I have tried doing 'adb reboot bootloader' but it only does the same as trying it from recovery mode.

The only other 'mode' that works is Samsung's Download mode' which I think only works with Odin.

Trying 'fastboot devices' during this screen yields no results.

Am I out of luck for trying to get this device rooted?

Thank you!

This guide for unlockable bootloader devices, B/N/0 models

 

[joancolmenares]

I assume this will trip Knox right?

 

[cjrivera04]

I assume this will trip Knox right?

Read the very first bullet, lol

 

[joancolmenares]

Read the very first bullet, lol

My very very bad... I kinda missed it lol

 

[Didgeridoohan]

@afaneh92 By the way, I'm curious: Why have you added the "Patch boot image" section? John's original Samsung instructions only include patching the AP, so I was wondering why you have this section in your text... From what I can see, users are reporting that John's original instructions work just as they should on the S21 devices (as long as you use releases from 21409 onwards).