• Device Model: Samsung Galaxy A21s (SM-A217F / SM-A217M / SM-A217N)
• Chipset / Platform: Samsung Exynos 850 (8nm)
• Storage Interface: eMMC 5.1
• Operating System: Android 10 / Android 11 / Android 12 (One UI 2.x / 3.x / 4.x)
• Target Recovery: TeamWin Recovery Project (TWRP) Custom Recovery
• Status: 100% Tested & Verified Working

Prerequisites & Important Warnings​

• Bootloader Unlock: The bootloader must be unlocked via Developer Options and Device Unlock Mode.
• Knox Warranty Void: Flashing a custom recovery permanently trips the Knox counter (0x1), permanently disabling Knox-dependent services (Samsung Pass, Secure Folder, Samsung Wallet/Pay).
• Data Loss: Bootloader unlocking and data formatting will erase all personal files. Create a full backup beforehand.
• Required Files & Tools:
  
  • Odin3 (v3.14.4 recommended).
  • Official Samsung Mobile USB Drivers installed on PC.
  • Verified twrp-a21s-exynos.tar file matching your model/bit.
  • vbmeta_disabled.tar to bypass Android Verified Boot (AVB).
  • Multidisabler ZIP file to disable dynamic filesystem encryption and stock recovery restore.

Step-by-Step Installation Instructions (Nasıl Yüklenir?)​

Step 1: Unlock the Bootloader​

1. Go to Settings > About Phone > Software Information and tap Build Number 7 times to unlock Developer Options.
2. Go back to Settings > Developer Options and enable OEM Unlocking and USB Debugging.
3. Power off the phone completely.
4. Press and hold Volume Up + Volume Down simultaneously and connect the phone to your PC using a USB cable.
5. On the warning screen, long-press Volume Up to enter Device Unlock Mode. Confirm the unlock (this wipes all user data and restarts the device).
6. Go through minimal setup, connect to Wi-Fi, and check Developer Options to confirm that OEM Unlock is greyed out and states "Bootloader already unlocked."

Step 2: Boot into Samsung Download Mode​

1. Turn off the phone completely.
2. Press and hold Volume Up + Volume Down together while connecting the USB cable to your PC.
3. Press Volume Up once briefly to enter Download Mode (Odin Mode).

Step 3: Flash TWRP & Patched VBMeta via Odin​

1. Launch Odin3 as Administrator on your PC. The ID:COM box will light up in light blue.
2. In the USERDATA slot, select vbmeta_disabled.tar.
3. In the AP slot, select your twrp.tar file.
4. Go to the Options tab in Odin:
   
   • Keep F. Reset Time checked.
   • Uncheck Auto Reboot (Crucial: Prevents the device from auto-booting into One UI, which immediately overwrites TWRP with stock recovery).
5. Click Start and wait for Odin to display the green PASS! status.

Step 4: First Boot into TWRP & Disable Encryption​

1. Unplug the USB cable.
2. Force restart the device by pressing and holding Volume Down + Power.
3. The exact instant the screen goes dark, immediately switch fingers and hold Volume Up + Power (keep connected to a PC via USB cable if your One UI version requires a USB handshake to access recovery).
4. Release the buttons once the TWRP splash screen appears.
5. Inside TWRP:
   
   • Swipe to allow system modifications.
   • Go to Wipe > Format Data, type yes, and confirm (removes forced file-based encryption).
   • Go to Advanced > Terminal or flash the Multidisabler ZIP via Install to disable encryption checks and stock recovery restoration.
   • Optional: Flash Magisk.zip via Install for permanent root access.
6. Go to Reboot > System.