[Android 11] Unofficial Lineage OS 18.1 for A21s

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New member
Nov 19, 2021
u7 recovery from android 12 post works for me.
android 11 oct security update last.

*need a dual sim variant.
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Jul 9, 2020
Does the binary 6 recovery work for 7? or it's just as good as dead if you already updated to u7 or s7 , idk but this phone has no official root add to that the dead Fastboot and non existing/normal user friendly (someone who isn't a Samsung dev or technician) s switch edm , and rebooting outside of Magisk causes softbrick same goes to power off (which makes on firm manual zip flashers pointless)
edit: this rom is a real life saver for those who don't mind the hotspot and other small issues so far so good no custom kernel yet great.
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New member
Nov 19, 2021
Does the binary 6 recovery work for 7? or it's just as good as dead if you already updated to u7 or s7 , idk but this phone has no official root add to that the dead Fastboot and non existing/normal user friendly (someone who isn't a Samsung dev or technician) s switch edm , and rebooting outside of Magisk causes softbrick same goes to power off (which makes on firm manual zip flashers pointless)
my binary before odin is u7 i think, u5&u6 binaried failed me in odin.
u7 works, I followed all other steps from this post. I just picked U7 from the other post.


Jul 9, 2020
i didn't see any video of downgrading from 11 to 10 from gsi or rom yet.
edit: I'm not sure if there are any official builds or interest gonna be given to this phone when you consider the major fbe issue which blocks twrp.
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Senior Member
May 1, 2015
hi, i need some help. I have gotten the u7 recovery for my device (a217f / dsn) I can install it, but I can't install lineage 18.1 it stays on the logo with the red letters and the yellow triangle. Do you know what it is due to?


New member
Jan 17, 2022
Hello all,
i tried follow the Instruction from the beginning post. In the Flash screen with "Downloading... Do nor Turn off target" ist show under warranty on the Top
left screen:
"OEM Lock is off"
"B:7 K:7 S:7"
"Carrier ID EUX"
Can anybody me explain Step by step how do and what i to do patch to use the LineOS Recovery image? the U5 and U6 Binary cant i use. In the vbmeta tar archiv i delete this "vbmeta" file and flash this with Odin? I dont need vbmeta?

I tried things. Now i have the LOS Recovery. Added and Sendded the lineage-18.1-20210902-UNOFFICIAL-a21s and gapps to the phone and this is installed how the pics in the Start Post (Script Successfull etc..). After Wipe Sys and Cache and Reboot the Phone doesnt boot and hangs with the Red Warning Message and Yellow Warning Sign under the Samsung A21s Logo.

doesnt work LOS with Binary S7?....
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Feb 19, 2022
Any chance there's a working U7 Lineage recovery?

The Available U7 on this Forum has a Bug that causes the phone to go on a bootloop.


New member
Apr 10, 2022
Hi, I have just done the process, and after make the wipe reset, I am currently stuck on Samsung Galaxy A21S Logo.... How can I recovery the phone??

Best regards.


Senior Member
Sep 2, 2013
Hi, I have just done the process, and after make the wipe reset, I am currently stuck on Samsung Galaxy A21S Logo.... How can I recovery the phone??

Best regards.
I think you have to reflash the stock rom. There's plenty of videos about it on youtube, you have to download the rom that corresponds to your phone and then flash it with odin.

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    On Lineage 18, I patched the kernel so that it would have no problem with the official Magisk app.
    Therefore, you DON'T need to use a version that has been modified for A21s.
    If you want to have root, you can get the Official Magisk App.

    1. Download & Install Magisk from the official source.
    2. Select Install. When it asks you to select the boot image, choose the boot image from the Lineage OS ROM file that you downloaded from the step above. After patching the boot image, move & rename it to something you can type easily (ex. /sdcard/rooting.img)
    3. Enable developer settings (Settings->About phone->Tap on build number)
    4. Go to developer settings and enable USB debugging & root permissions for usb debugging.
    5. Connect the phone to the PC.
    6. Open the command prompt, and type "cd <the folder where you installed adb>. After that, type "adb root". If the phone asks you for permissions for USB debugging, allow it.
    7. After the adb shows "Restarting adbd as root", type "adb shell dd if=/sdcard/<the path to saved boot image>" of=/dev/block/by-name/boot". The output should be something like
    " *** records in
    *** records out
    *** bytes (** M) copied, *** s, **M/s"

    8. After seeing the output above, reboot the phone. After rebooting, it should be rooted.
    By installing this custom ROM, you are VOIDING your warranty. Also, installation of this ROM WILL TRIP KNOX PERMANENTLY, and render apps such as Samsung Health, Private Folder, (+ any apps that depend on KNOX) useless until you get the phone's motherboard replaced at the Samsung C/S center.
    Although this software is released in the hope that it will be useful, there is NO GUARANTEE that installing this will not cause any harm to your device. I TAKE NO RESPONSIBILITY FOR ANY BRICKED DEVICES, DAMAGED HARDWARE, OR ANY OTHER PROBLEMS CAUSED BY THIS ROM. You are using this ROM at YOUR OWN RISK. I strongly recommend that you DO NOT continue to the steps below UNLESS YOU FULLY UNDERSTAND WHAT YOU ARE DOING.
    While this ROM has been tested with South Korean variant of Galaxy A21s (SM-A217N, CSC changed from LUC->SKC), please keep in mind that it hasn't been tested on any other variant (such as A217F, A217M.)
    I would like to express special thanks to all the developers who contributed to the LineageOS port for Galaxy Tab S6 Lite + all the other developers who contributed to sepolicy & hardware parts for Samsung SLSI (Exynos) devices. Porting LineageOS to A21s would have been much harder without them.

    After doing some research on this device, I was able to port LineageOS. The original sources are based on Galaxy Tab S6 Lite Wi-Fi version (gta4xlwifi), with some heavy modifications made for the A21s. In the process, I was able to fix some of the problems that were found on GSI (MTP, Fingerprint removal issues, NFC, Wi-Fi hotspot and direct), and added in some enhancements to the kernel.

    Unfortunately, installation of this ROM requires Lineage Recovery, and since FBE (File-based-encryption) is enabled by default, it is incompatible with the TWRP.




    - Cell Broadcast (Emergency Messages) is broken in South Korea. The phone shows notifications, but the messages appear broken. Not sure about other countries. FIXED in South Korea as of 2021/9/2. However, its functionality in other countries hasn't been tested.
    - Samsung's Proprietary Apps
    - In order to use Wi-Fi Direct, you need to install a Wi-Fi direct sharing app from Google Play, as LineageOS doesn't have a sharing app installed by default
    - Auto Brightness (The phone doesn't have the sensors for it anyway)
    - On very rare occasions(probably once in more than 20 boots), the device's RIL (Phone calls, Data) might start up late when booting. If you see "No service" after booting, please wait for 30-60 seconds.
    - VoLTE & VoWifi(not tested) - Unfortunately, this is located deep within Samsung's framework. AOSP-based roms for other Samsung devices don't support it either. Someday, this might be fixed.....

    - Everything Else

    Device Source Tree: android_device_samsung_a21s, android_device_samsung_universal3830-common
    Kernel: android_kernel_samsung_universal3830-common

    Instructions for Installation:

    1. BEFORE INSTALLING, make sure that you have UNLOCKED the bootloader of your device. This is a great guide that show how to do it. Also, the phone must be on the Stock ANDROID 11. If you are on binary U6, please use the recovery tar for U6.

    2. Download the Lineage Recovery, ROM, Google Apps, ADB, and Odin. Unzip ADB and Odin to somewhere appropriate.

    - ROM
    - Recovery / Recovery(for U6)
    - Google Apps
    - ADB
    - Odin

    3. Enable USB Debugging on the device. Go to settings->About phone->Software information, and tap the build number several times until you see the notification that the devloper settings have been enabled. After enabling developer settings, go to settings->developer settings and check USB debugging.



    4. Open Command Prompt, and type "cd <the path where you saved ADB to>".


    4-1. As a test, type "adb devices". After typing it, the phone should show a screen that asks you to grant permissions for USB debugging. Select Yes.

    5. On the phone, start holding down the Volume Up and Down keys. KEEP THE KEYS PRESSED UNTIL THE PHONE REBOOTS AFTER YOU TYPE THE COMMAND IN THE NEXT STEP.


    6. While holding the keys down. type in the command "adb reboot recovery" on the command line.


    11. After the phone reboots into download mode, press volume up to continue. Make sure that you see the "OEM LOCK: OFF" before continuing.


    12. Open Odin. After opening Odin, click on AP, and select the Lineage Recovery Tar file that you downloaded in the step 2. After that, click on Start.




    13. After a few seconds, if everything goes well, Odin should show "PASS" and the device should reboot into Lineage Recovery. After the device enters recovery, tap on Apply update->Apply from ADB. In some cases, touchscreen may be unresponsive or slow. If that happens, use Volume Keys to navigate and Power key to select. KEEP THE DEVICE CONNECTED TO THE COMPUTER.



    14. After choosing Apply from ADB, type "adb sideload <the path where you saved the ROM file>" on the command prompt and press enter.


    Hello everyone,
    I'm really sorry for not responding for several days. Have been busy recently, since the new semester started ㅠㅠ

    After some research, I think I found out causes of several bugs (including audio)
    Also, I think I need to clean up the sources for this ROM, as I haven't done so since I started working on it in July. Some thing have gotten messed up in the middle.
    Right now, I'm completely reworking the ROM. This might take several days.
    Again, I'm really sorry for all the inconveniences caused by the bugs. I'll try my best to do this asap.

    + On the volume issues:
    While testing on my device, I found out that the maximum volume was smaller than that of stock (when compared to S21 or S7). Disabling AudioFX (or changing it into different setting other than "Small Speaker") made the sound louder. However, I also found out that the sound was louder when using some libs from stock, so I will try to get it fixed that way on the next release. Until then, disabling audiofx might be a temporary workaround for this problem.
    15. If everything goes right, the device should show "script succeeded: result was [1.000000]" While ADB may show errors such as "Failed to read command" at 47%, this is no problem as long as the device says that the script succeeded.


    16. Now it is time to install Google apps. On the phone, tap on Apply from ADB again, and on the computer, type "adb sideload <the path where you saved Google apps to>" and press enter.



    17. After about 1-2 minutes, installation should be complete. Again, ADB might show "Failed to read command" errors. As long as the phone says that it was success, this is no problem. After installing, click on the "back" icon shown below.


    18. Choose Wipe data/factory reset, and reboot the device.


    19. If everything went well, the phone should reboot into LineageOS. Set up the device and Enjoy!

    I would like to thank everyone for sharing their reviews of this ROM.
    This ROM is getting updated every week, so if you are experiencing some bugs, it might be fixed by installing the latest build from the OP.

    So far the changelogs since July 29 release have been:
    - Resolved errors related to thermal control and battery
    - Updated GPU drivers
    - Added code to lessen battery usage
    - Fixed some issues with Camera (saved pictures were way bigger than those from stock)
    - Added support for Binary version U6
    - Added support for Dynamic System Updates
    - Fixed Camera problems in DSU mode, and increased DSU data partition to make it more usable
    - For every build, synced in latest LineageOS source code to get the latest Lineage OS changes and Android security patches. (ex. from 08/07 builds, security patch level was increased from 2021-07 to 2021-08)

    As of now, I'm trying to figure out the cause of the volume and crash issues. Unfortunately, my device is not affected by these issues, so it is somewhat tricky to find a solution to this. (A217N's hardware is somewhat different from A217M/A217F, as it has lower RAM/Storage, no dual SIM, and some CSC-related changes for Korean market. One possible reason for the bugs may be due to the fact that the blobs / kernel settings were for A217N)

    Would it be possible for anyone to get the log from UI crash (or any other instabilities such as reboot)? In order to get the log, when you are experiencing UI crash, please follow these steps:
    1. Connect your device to ADB
    2. Open command line or terminal
    3. run 'adb logcat -b all -d > log.txt'
    and post the log.txt on this thread. It would give a very useful clue in solving this problem.

    Also, if you experienced a reboot/kernel panic/BSOD/or any other similar issues, please follow these steps:
    1. In the developer settings, enable 'Rooted Debugging'
    2. Connect your device to ADB
    3. Open command line or terminal
    4. run 'adb root' and wait for a second
    5. run 'adb shell cat /proc/last_kmsg > last_kmsg.txt'
    and post the last_kmsg.txt on this thread.

    I am very sorry for the inconvenience caused by the bugs. It would be very thankful if you could give a log that shows the problem.