Last Updated: June 4, 2026
Getting your SM-G998B/DS back to normal is a simple process when you use the official Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware. This page provides all the necessary files and instructions for FRP bypass, hard resets, IMEI repair, and complete flashing.
Device: Samsung Galaxy S21 Ultra 5G SM-G998B/DS | Chipset: Exynos 2100 (5 nm) | Flash Tool: Odin
Android: Android 15, One UI 7 | File Type: .tar.md5 / ZIP (Contains AP, BL, CP, CSC files for Odin)
⚠ Warning: Flashing erases all data. Back up first.
Samsung Galaxy S21 Ultra 5G SM-G998B/DS Firmware (Flash File) Drivers, Tools & Guide
Flashing a Samsung phone with Odin is a simple task once you understand the steps. I have organized everything you need right here, including the correct Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware, the proper Odin version, and clear instructions.
Before you begin, check if a Samsung account is currently signed in on the phone. You must sign out of it first to prevent Knox security from triggering, which causes a KG lock that takes much longer to fix. Samsung firmware files use the .tar.md5 format. Once you extract the ZIP folder, look for files labeled AP_*, BL_*, CP_*, and CSC_* (or HOME_CSC_*). If these files are missing, the package is incorrect.
Your Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware arrives as a compressed ZIP archive. You can unpack it using WinRAR or 7-Zip. Inside the folder, verify that you have files like AP_*.tar.md5, BL_*.tar.md5, CP_*.tar.md5, and CSC_*.tar.md5 (or HOME_CSC_*.tar.md5). If the contents look different, you might have downloaded the wrong package for your specific phone.
Remember that installing stock software completely wipes your phone. This is exactly what fixes persistent software glitches, FRP locks, app crashes, sluggish performance, forgotten passwords, devices stuck on the logo, connectivity bugs, battery drain, and soft brick conditions.
Hard Reset Samsung Galaxy S21 Ultra 5G SM-G998B/DS
You can perform a factory reset on the Samsung Galaxy S21 Ultra 5G SM-G998B/DS without a computer by turning the device off, then pressing and holding Volume Up + Power (or Volume Up + Home + Power on older models with a physical home button) until the recovery menu loads. Scroll down to “Wipe Data/Factory Reset” using the volume keys and press the Power button to select it.
Performing this reset deletes all personal files and returns the Samsung Galaxy S21 Ultra 5G SM-G998B/DS to its original factory settings. This process resolves common glitches like system lag, application errors, lost screen lock passwords, and continuous bootloops. If the phone still misbehaves after the reset, the full Odin installation guide in the next sections will help.
Samsung Galaxy S21 Ultra 5G SM-G998B/DS FRP Bypass
The most reliable method to bypass FRP on the Samsung Galaxy S21 Ultra 5G SM-G998B/DS is to use a free Android apps launcher to access the settings menu during the initial setup. If you see a Google account lock after a reset or flash, our free Android apps launcher will help you get past it quickly. This is exactly why removing your Google account before a flash is the best practice.
Why Do We Need Samsung Galaxy S21 Ultra 5G SM-G998B/DS Firmware?
Flashing the official software helps resolve system errors, update the Android version, and remove software locks on your Samsung Galaxy S21 Ultra 5G SM-G998B/DS. Samsung phones always use Odin for this, no matter which processor they have. Here are the main reasons to install it:
- Remove pattern locks or disable a frozen device.
- Upgrade the operating system to the newest version supported by the manufacturer.
- Eliminate freezing, lag, and continuous restarting on your SM-G998B/DS Galaxy S21 Ultra 5G.
- Fix failed over-the-air updates and abnormal battery drain.
- Return to the original factory state to maintain your warranty status.
- Repair a phone that will only boot into the recovery screen.
- Clear KG lock or Knox errors caused by an interrupted or incorrect installation.
Learn more about stock ROMs and why flashing works.
Choosing the Right Firmware Version
Selecting the correct software version requires checking your exact model number, region code, and binary level before downloading anything. Installing the wrong file can cause serious issues, so take your time with these steps:
- Identify Your Exact Model Number: Go to Settings › About Phone and note your full model number (e.g. SM-G998B/DS). The letter suffix matters, U/U1 = USA, W = Canada, N = Korea, B/F = International/Global. Flashing firmware built for a different variant can cause issues.
- Match the CSC (Region): The 3-letter region code in the firmware filename must match your device. Check Settings › About Phone › Software Information for your current CSC, or look at the Service Provider line in Download Mode. Common codes: XAA (US), BTU (UK), INS (India), SER (Russia).
- Check the Binary Level: Look at the version string in your current firmware (e.g.
XXU9BZDP, the number after the letters is the binary level). You cannot downgrade to a lower binary level. If your device is on Binary 9, only flash Binary 9 or higher firmware. - Confirm the Build Date: The last 4 characters of the PDA version encode the build date, first character is the year (A=2024, B=2025, C=2026), second is the month (A=Jan through L=Dec).
- Verify in Download Mode: Power off, hold Volume Down + Power to enter Download Mode. This screen shows your exact model, CSC, and current firmware version, use this to confirm before flashing.
Firmware Details for Samsung Galaxy S21 Ultra 5G SM-G998B/DS
Here is a quick overview of the official firmware specifications:
| Firmware Information | Details |
|---|---|
| Device Model | Samsung Galaxy S21 Ultra 5G SM-G998B/DS |
| Firmware Version | V00 |
| File Size | 716.82 MB |
| Android Version | Android 15, One UI 7 |
| Platform | Exynos 2100 (5 nm) |
| Release Date | Released 2021, January 29 |
| Region | Global, Africa and Asia |
| File Type | .tar.md5 / ZIP (Contains AP, BL, CP, CSC files for Odin) |
Which Firmware Version Should I Download?
This is the question I get asked most often in the comments, so I put together a simple guide. Find your situation in the table and go straight to the right file:
| Your Situation | What I Recommend |
|---|---|
| Phone is completely dead or stuck on logo | the latest version, download this one. It is the latest Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware available. |
| FRP / Google account lock only | See the FRP bypass guide above, you likely do not need the full firmware for this. |
| Not sure which region/CSC to download | Check Settings › About Phone › Software Information for your current CSC, or enter Download Mode (Volume Down + Power), it shows the CSC on screen. Match the 3-letter code (e.g. XAA, BTU, INS) to the firmware filename. |
| Phone slow after a recent OTA update | Try the next older version, sometimes the latest OTA introduces new bugs and an older build runs better. Make sure the binary level is the same or higher than what your device currently has. |
| IMEI missing after a previous flash | Re-flash the latest version first, then follow the IMEI repair guide. Do not skip the reflash. |
| the latest version failed with a flash error | Try the next older version instead and double-check your AP/BL/CP/CSC file assignments in Odin before assuming the firmware is the problem. |
| Restoring to factory / warranty repair | the latest version, clean state, fresh start. |
To tell which Samsung firmware is newer, look at the last 4 characters of the PDA version string (e.g. S938BXXU9CZDP). The first character is the year (A=2024, B=2025, C=2026), the second is the month (A=Jan, B=Feb… L=Dec, Z=final stable), and the last two are the revision (0-9 then A-Z, where Z is highest). But before comparing dates, always check the binary level: the digit just before the date code (e.g. XXU9CZDP = Binary 9). You cannot downgrade to a lower binary level. If your device is on Binary 9, only flash Binary 9 or higher. Also make sure the 3-letter CSC code in the firmware matches your device region.
Download Samsung Galaxy S21 Ultra 5G SM-G998B/DS Firmware
You can download the official stock firmware for your Samsung Galaxy S21 Ultra 5G SM-G998B/DS directly from the table below. The most recent release available is the latest version. Once the download finishes, double-check that the file size matches the details listed earlier. A mismatched file size usually means the download was interrupted, and flashing an incomplete file will cause more errors.
| Software Details | Download Link | Members Link |
|---|---|---|
|
File Name: COMBINATION_FAC_FA81_J610GUBU1ARI4_FACFAC_CL14321305_QB19776235_REV00_user.rar Size: 716.82 MB | Download Link | Download Link2 |
Only download firmware that is fully compatible with your exact device model. See the firmware selection guide above if you are not sure.
- Your model number is a variant of SM-G998B/DS with a different letter suffix. Check About Phone carefully, one letter difference can cause a failed or broken flash.
- Your chipset differs from Exynos 2100 (5 nm). Confirm in recovery mode before proceeding.
- You downloaded the file from a source other than this page.
- The file size differs significantly from the sizes listed in the table above, a size mismatch usually means a partial download, which will fail mid-flash.
Prerequisites for Samsung Galaxy S21 Ultra 5G SM-G998B/DS Firmware
Preparing your computer and phone before opening Odin ensures the installation process goes smoothly without interruptions. Two common mistakes people make are leaving a Samsung account signed in, which triggers KG lock, and using a low-quality charging cable that loses connection halfway through. Always use a high-quality data cable for this process.
- Back Up IMEI Numbers: Dial *#06# and write down both IMEI numbers now. You will need these if you need to restore your IMEI after flashing.
- Remove Google Accounts: Sign out of all Google accounts to prevent FRP lock after flashing.
- Remove Samsung Accounts: Sign out of all Samsung accounts to avoid KG lock.
- Back Up Your Data: Back up everything, photos, contacts, WhatsApp chats, important files. Flashing wipes the device completely.
- Charge Your Device: At least 50% battery. A device that powers off during a flash is very difficult to recover.
- USB Cable & PC: Use a proper data USB cable, not a charge-only cable, and a Windows computer with available USB ports.
- Install Required Drivers:
How to Install Firmware on Samsung Galaxy S21 Ultra 5G SM-G998B/DS
You can install the new system files on your phone by using the Odin flash tool on a Windows PC. A helpful tip is to leave “Auto Reboot” and “F. Reset Time” checked in Odin, as these options provide the cleanest result. If you need help picking an Odin version, visit our Odin versions page. Older phones sometimes respond better to older Odin builds.
- Download and Extract:
- Download the correct firmware package from the links above.
- Extract the ZIP to a simple folder path, avoid paths with spaces or special characters, as some flash tools have trouble with them.
- Install the Listed Drivers:
- Confirm all drivers listed above are installed and that your PC has been restarted since installation. Skipping the restart is a common reason drivers do not work correctly.
- Load the Firmware File:
- In Odin, click “BL” and select the BL_*.tar.md5 file. Click “AP” and select the AP_*.tar.md5 file. Repeat for “CP” and “CSC”. Use HOME_CSC to keep data, or CSC for a clean flash.
- Connect Your Device:
- Enter Download Mode: Turn off your phone, then hold Volume Down + Power (add Home button on older models) until the warning screen appears. Press Volume Up to confirm and enter Download Mode.
- Connect your phone to your PC via USB. Odin should show “Added..” in the log area, this means your device is detected.
- Start Flashing:
- Click the “Start” button to begin.
- Do not disconnect, move the cable, or touch the device until the process is fully complete. Disconnecting mid-flash is how devices get bricked.
- Wait and Reboot:
- Once flashing finishes successfully, disconnect the device.
- Power on your device. The first boot will take longer than usual, give it up to 8 minutes.
Video Guide for Flashing
What to Expect After Flashing Samsung Galaxy S21 Ultra 5G SM-G998B/DS Firmware
Many people worry that something went wrong when the phone is actually behaving normally. Here is what to expect after a successful Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware installation:
- How to confirm success: Odin will display “PASS.” in a green box in the top-left corner. This message means the process finished correctly.
- Initial startup requires 3 to 8 minutes: Please do not restart the phone manually. The system is configuring itself for the first time, and interrupting it can cause a bootloop.
- The device may feel warm: This is completely normal during the first startup. It will cool down once the initial setup finishes.
- Your applications will be missing: A flash wipes everything. You will need to download your apps again from the Play Store. If you have a Google backup, the phone will offer to restore them.
- Check your IMEI immediately: Dial *#06# right after setup, before inserting a SIM card. If the screen shows “unknown” or “null”, follow the IMEI repair guide below.
- Add your Google account carefully: If you forgot to remove your Google account earlier, you might see an FRP prompt. Enter your credentials during the setup wizard rather than going through the Settings app later.
- Network connections: Wi-Fi, Bluetooth, and mobile data should work immediately. If mobile data fails, navigate to Settings › SIM and Network to manually input your APN details, as the flash might have erased them.
- Handling a bootloop: If the phone restarts continuously after the first boot, boot into recovery mode and perform a factory reset (see the hard reset guide above). This usually clears out conflicting data from the old system.
- Samsung Smart Switch updates: After applying the Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware, Smart Switch might find extra updates. Allow it to install them to ensure you have the newest security patches.
Missing IMEI or Corrupt Baseband on Samsung Galaxy S21 Ultra 5G SM-G998B/DS After Flashing?
A missing baseband or IMEI usually happens when the EFS partition gets corrupted during the flashing process. The EFS partition holds your IMEI and network details. Please note that writing a fake IMEI is illegal in many regions, so only use these tools to restore your original number. Software like ChimeraTool or BFT can fix this. Verify your local regulations first.
Video Guide: How to repair IMEI
Common Issues When Flashing Samsung Galaxy S21 Ultra 5G SM-G998B/DS
Most flashing errors occur due to incorrect file selection, bad USB connections, or missed preparation steps. Here are the most frequent problems and how to solve them:
- Odin Displays “FAIL” Instead of “PASS”:
- This generally means the software region or model does not match your phone. Verify your exact model number in Settings › About Phone before trying again. Even a single incorrect letter will cause a failure.
- Odin Does Not Detect the Phone:
- Reinstall the Samsung USB drivers and ensure the device is in Download Mode. Switching to a different, higher-quality USB cable often fixes connection drops.
- Knox or KG Lock Activated:
- This occurs if a Samsung account remained logged in before the flash, or if unofficial software was used. Always log out of Samsung accounts beforehand. If KG lock is already active, you typically need a specialized unlocking service.
- Continuous Bootloop:
- Boot into recovery mode by pressing Volume Up + Power, then choose to wipe data. This deletes leftover files from the previous system that might be causing the conflict.
Frequently Asked Questions
Q1: Will flashing the Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware erase my data?
A: Yes, installing this software with Odin returns the phone to its factory settings, including the default Android 15, One UI 7 configuration. Every app, photo, contact, and account will be deleted. Make sure to create a backup beforehand, because you cannot recover the data once the process finishes.
Q2: Is this firmware compatible with other Samsung models?
A: No, this specific package is made exclusively for the Samsung Galaxy S21 Ultra 5G SM-G998B/DS using the Exynos 2100 (5 nm) processor. Even a slightly different variant of the SM-G998B/DS might use entirely different internal hardware. Installing the wrong files can severely damage your phone. Always confirm your exact model in Settings › About Phone.
Q3: Can I downgrade from the latest version to an older firmware version?
A: While it is sometimes possible on Exynos models, I advise against it. Rolling back can create security vulnerabilities and app crashes on Android 15, One UI 7. If the newest release is giving you trouble, leave a comment below so we can find a safer solution.
Q4: What should I do if I encounter an FRP lock after flashing?
A: You can use our free Android apps launcher to resolve it. FRP activates on the Samsung Galaxy S21 Ultra 5G SM-G998B/DS when a Google account remains logged in prior to the flash. Removing the account beforehand is the easiest way to prevent this.
Q5: Are custom ROM options available for the Samsung Galaxy S21 Ultra 5G SM-G998B/DS?
A: This article focuses entirely on official Samsung stock software. The availability of custom ROMs for the Samsung Galaxy S21 Ultra 5G SM-G998B/DS depends on whether developers have open-source kernel access for the Exynos 2100 (5 nm) chip. You can check our Custom ROMs page or the XDA Developers forum for community-built options.
Q6: My Samsung Galaxy S21 Ultra 5G SM-G998B/DS is not detected by Odin. What should I do?
A: Focus on the drivers first. Reinstall the Samsung USB drivers, reboot your computer, and try again. Moving the cable to a USB 2.0 port instead of USB 3.0 often helps, as Samsung phones communicate more reliably on older ports. Temporarily disable your antivirus software. If the problem continues, leave a comment with the exact error message and I will assist you.
Q7: How do I enter recovery mode on my Samsung Galaxy S21 Ultra 5G SM-G998B/DS?
A: Turn the phone completely off, then press and hold Volume Up + Power together until the recovery menu appears. If you are using an older Samsung phone with a physical home button, press Volume Up + Home + Power. The recovery screen will show the current build number for your Samsung Galaxy S21 Ultra 5G SM-G998B/DS, which helps you verify the installed version.
Q8: My IMEI shows “unknown” after flashing the Samsung Galaxy S21 Ultra 5G SM-G998B/DS. Is my phone permanently damaged?
A: No, your phone is not broken, and the issue is repairable. Read the IMEI repair guide in the troubleshooting section above. For Samsung phones, you should check the EFS partition for errors first. Remember to keep your SIM card out of the tray until the IMEI is fully restored.
Q9: How long does it take to flash Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware?
A: The actual installation inside Odin usually requires 3 to 10 minutes, depending on the file size and your USB transfer speed. The first startup after the installation takes an additional 3 to 8 minutes. Do not unplug or restart the phone during either phase. If the Odin progress bar stops moving, wait a few extra minutes before assuming it failed.
Final Thoughts on Samsung Galaxy S21 Ultra 5G SM-G998B/DS Firmware
Installing the official system files is the most reliable way to fix software problems and restore your phone to working order. If you followed the instructions carefully, your device should now be running smoothly on a clean build of the Samsung Galaxy S21 Ultra 5G SM-G998B/DS firmware.
If you ran into an error or a specific step did not work, please leave a comment below. Include the exact error message, the step you are currently on, and the steps you have already attempted. I read every comment and will help you resolve the issue.
If you found this tutorial helpful, please share it with others who might need assistance with their phones.
Browse all Samsung firmware downloads for more devices.
Disclaimer: Flashing stock firmware is performed at your own risk. Follow the instructions on this page carefully. I cannot be held responsible for any damage to your device, but I will always try to help if something goes wrong.
