Last Updated: June 3, 2026
The official Samsung Galaxy S21 Ultra 5G SM-G998B firmware is your primary tool for fixing software problems on this specific model. This guide provides all the necessary flash files, drivers, and instructions to get the phone fully functional again.
Device: Samsung Galaxy S21 Ultra 5G SM-G998B | Chipset: Exynos 2100 (5 nm) | Flash Tool: Odin
Android: Android 15, One UI | 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 Firmware (Flash File) Drivers, Tools & Guide
Installing the Samsung Galaxy S21 Ultra 5G SM-G998B firmware requires the correct Odin version, the right flash files, and a careful step-by-step approach. Flashing a Samsung phone using Odin becomes a simple routine once you understand the process. On this page, you will find the exact firmware file, the matching Odin software, and the proven steps to complete the job.
Before you begin, check if a Samsung account is currently signed in on the phone. If it is, log out immediately. Skipping this step will trigger Knox security, leaving you with a KG lock that takes much longer to clear. Samsung firmware packages arrive in a .tar.md5 format. Once you extract the main ZIP folder, look for files labeled AP_*, BL_*, CP_*, and CSC_* (or HOME_CSC_*). If these specific files are missing, you have downloaded the wrong package.
The Samsung Galaxy S21 Ultra 5G SM-G998B firmware downloads as a compressed ZIP archive. Use WinRAR or 7-Zip to extract the contents. Inside, you should see AP_*.tar.md5, BL_*.tar.md5, CP_*.tar.md5, and CSC_*.tar.md5 (or HOME_CSC_*.tar.md5). Missing these files means the package is incorrect for your device.
Remember that installing stock firmware completely wipes the phone. This factory reset effect is intentional and clears out persistent software glitches, including FRP locks, application crashes, sluggish performance, forgotten screen locks, bootloops, connectivity bugs, and soft brick conditions.
Hard Reset Samsung Galaxy S21 Ultra 5G SM-G998B
A hard reset on the Samsung Galaxy S21 Ultra 5G SM-G998B is performed by holding the Volume Up + Power buttons together while the device is powered off to access the recovery menu. To execute a factory reset without a computer, turn the phone completely off. Press and hold Volume Up + Power simultaneously until the recovery menu loads. Use the volume rocker to highlight “Wipe Data/Factory Reset” and press the Power button to confirm your selection.
Performing this reset wipes all personal data and returns the Samsung Galaxy S21 Ultra 5G SM-G998B to its factory defaults. It resolves the majority of common software complaints like system lag, random reboots, and lost passwords. If the phone still misbehaves after the wipe, proceed to the full Odin flashing tutorial below.
Samsung Galaxy S21 Ultra 5G SM-G998B FRP Bypass
The most reliable method to bypass FRP on the Samsung Galaxy S21 Ultra 5G SM-G998B involves using a dedicated Android apps launcher to access device settings during the initial setup. Following a factory reset or a firmware flash, Google Factory Reset Protection (FRP) might lock the phone. You can use our free Android apps launcher to quickly get around this security check. This is exactly why removing your Google account before a flash is always the best practice.
Why Do We Need Samsung Galaxy S21 Ultra 5G SM-G998B Firmware?
Flashing the Samsung Galaxy S21 Ultra 5G SM-G998B firmware is necessary to resolve deep system errors, update the operating system, or recover a bricked device. Regardless of the internal processor, Samsung phones rely on Odin to install official software. Installing the official firmware resolves a wide range of operational issues:
- Unlock a disabled or frozen handset.
- Upgrade the operating system to the newest supported build.
- Eliminate system freezing, lag, and continuous bootloops.
- Fix failed over-the-air updates and abnormal battery drain.
- Reinstall the original stock ROM to maintain warranty status.
- Rescue a phone that only boots into the recovery environment.
- Clear KG lock or Knox errors resulting from a failed or interrupted flash.
Read more about stock ROMs and why flashing works.
Choosing the Right Firmware Version
Selecting the correct firmware version requires matching your exact model number, region code, and binary level to the downloaded files. Verifying your files before pressing the start button in Odin saves you from major headaches. Flashing an incompatible file is a tough mistake to fix:
- Identify Your Exact Model Number: Go to Settings › About Phone and note your full model number (e.g. SM-G998B). 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
The official firmware specifications for the Samsung Galaxy S21 Ultra 5G SM-G998B include Android 15, One UI, and the Exynos 2100 (5 nm) chipset. Here is a quick overview of the official firmware specifications:
| Firmware Information | Details |
|---|---|
| Device Model | Samsung Galaxy S21 Ultra 5G SM-G998B |
| Firmware Version | N/A |
| File Size | 6.73 GB to 6.95 GB |
| Android Version | Android 15, One UI |
| 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?
You should download the firmware version that directly corresponds to your specific issue, such as choosing the latest build for a dead phone or an older build for OTA rollback. Deciding which file to grab is a common question. Use this reference table to match your current situation with the correct download:
| 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 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 Firmware
You can download the official Samsung Galaxy S21 Ultra 5G SM-G998B firmware directly from the links provided below. The most recent release available is the latest version. Once the download finishes, compare the file size against the details listed earlier. A mismatch in file size points to a corrupted or incomplete download, which will only cause trouble in Odin.
| Software Details | Download Link | Members Link |
|---|---|---|
|
File Name: SM_G998B_G998BXXS6EWBB_4_file.rar Size: 6.88 GB | Download Link | Download Link2 |
| File Name: SM_G998B_G998BXXS5DWA4_4_file.rar Size: 6.73 GB | Download Link | Download Link2 |
| File Name: SM_G998B_G998BXXU4CVD2_4_file.rar Size: 6.95 GB | Download Link | Download Link2 |
| File Name: SM_G998B_G998BXXS3BULC_4_file.rar Size: 6.78 GB | 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 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 Firmware
Preparing to flash the Samsung Galaxy S21 Ultra 5G SM-G998B firmware requires backing up data, removing accounts, and installing the correct USB drivers. Run through this checklist before launching Odin. Two issues frequently trip people up: forgetting to sign out of a Samsung account (which causes KG lock) and using a cheap charging cable that drops the connection mid-flash. Always use a high-quality data cable.
- Back Up IMEI Numbers: Dial *#06# and record both IMEI numbers. Keep these safe in case you need to restore your baseband later.
- Remove Google Accounts: Sign out of all Google accounts to prevent FRP lock after the flash.
- Remove Samsung Accounts: Sign out of all Samsung accounts to prevent triggering KG lock.
- Back Up Your Data: Save your photos, contacts, and files elsewhere. Flashing wipes the internal storage completely.
- Charge Your Device: Ensure the battery is at least 50%. A power loss during a flash is tough to recover from.
- USB Cable & PC: Connect using a reliable data USB cable and a Windows computer with functional USB ports.
- Install Required Drivers:
How to Install Firmware on Samsung Galaxy S21 Ultra 5G SM-G998B
Installing firmware on the Samsung Galaxy S21 Ultra 5G SM-G998B is done by loading the extracted AP, BL, CP, and CSC files into Odin and initiating the flash. We will use Odin for this procedure. Leave “Auto Reboot” and “F. Reset Time” checked inside Odin to guarantee the cleanest result. If you need help choosing an Odin version, visit our Odin versions page. Certain older Samsung phones operate more reliably on older Odin builds.
- Download and Extract:
- Get the correct firmware package from the download section.
- Extract the ZIP file to a simple folder location. Avoid paths containing spaces or special characters, as Odin sometimes struggles to read them.
- Install the Listed Drivers:
- Double-check that all drivers listed above are installed. Restart your computer afterward, as skipping the restart often prevents the drivers from initializing properly.
- Load the Firmware File:
- Inside Odin, click “BL” and select the BL_*.tar.md5 file. Click “AP” and choose the AP_*.tar.md5 file. Do the same for “CP” and “CSC”. Select HOME_CSC if you want to keep your data, or regular CSC for a complete wipe.
- Connect Your Device:
- Boot into Download Mode: Turn the phone off, then press Volume Down + Power (add the Home button on older models) until the warning screen pops up. Hit Volume Up to enter Download Mode.
- Plug the phone into your PC. Odin should display “Added..” in the log box, confirming a successful connection.
- Start Flashing:
- Click the “Start” button.
- Leave the phone completely alone until the process finishes. Unplugging the cable mid-flash is a guaranteed way to brick the handset.
- Wait and Reboot:
- When Odin shows a successful completion, unplug the phone.
- Turn the device on. The initial boot sequence takes longer than normal, wait up to 8 minutes.
Video Guide for Flashing
What to Expect After Flashing Samsung Galaxy S21 Ultra 5G SM-G998B Firmware
After flashing the Samsung Galaxy S21 Ultra 5G SM-G998B firmware, expect a longer initial boot time, warm device temperatures, and a completely clean operating system. Many users assume the flash failed when the phone acts a bit strange immediately afterward. Here is exactly what is normal after applying the firmware:
- How to know the flash was successful: A green “PASS.” message will appear in the top-left corner of Odin. Seeing this means the installation worked perfectly.
- First boot takes 3 to 8 minutes: Do not pull the battery or force a restart. The system is configuring itself for the first time. Interrupting this setup leads directly to bootloops.
- The phone will feel warm during first boot: This is completely standard. The device will cool down shortly after the initial setup finishes.
- All your apps are gone: This is the intended result of a clean flash. Download your apps again from the Play Store. If Google backup was enabled, the setup wizard will offer to restore your applications.
- Dial *#06# immediately after setup: Verify your IMEI numbers before inserting a SIM card. If the screen reads “unknown” or “null”, consult the IMEI repair guide below immediately.
- Be careful when re-adding your Google account: Failing to remove your Google account prior to flashing triggers FRP. Add the account during the initial setup wizard rather than through the Settings menu later.
- Wi-Fi, Bluetooth, and mobile data: These features should function right away. If mobile data fails, navigate to Settings › SIM and Network and input your APN details manually, as the flash sometimes wipes carrier configurations.
- Stuck in a bootloop after first boot? Boot into recovery mode and execute a factory reset, refer to the hard reset guide above. This occasionally happens when leftover files conflict with the new OS, and it does not mean the firmware is bad.
- Samsung Smart Switch: Following the Samsung Galaxy S21 Ultra 5G SM-G998B firmware installation, Smart Switch might recommend extra updates. Allow it to install them to ensure your phone has the newest regional security patches.
Missing IMEI or Corrupt Baseband on Samsung Galaxy S21 Ultra 5G SM-G998B After Flashing?
A missing IMEI or corrupt baseband on the Samsung Galaxy S21 Ultra 5G SM-G998B usually indicates a wiped or damaged EFS partition. When an IMEI disappears after a flash, the EFS partition, which holds your carrier settings and IMEI data, is usually corrupted. Restoring an IMEI that does not belong to the original device is illegal in many regions, so only restore the phone’s original numbers. Software like ChimeraTool or BFT can fix this. Check your local regulations first.
Video Guide: How to repair IMEI
Common Issues When Flashing Samsung Galaxy S21 Ultra 5G SM-G998B
Common issues when flashing the Samsung Galaxy S21 Ultra 5G SM-G998B include Odin failing to recognize the device, KG lock triggers, and post-flash bootloops.
- Odin Shows “FAIL” Instead of “PASS”:
- This generally happens when the firmware region or model does not match the phone. Verify your exact model under Settings › About Phone before loading any files. A single incorrect letter in the model code ruins the flash.
- Samsung Galaxy S21 Ultra 5G SM-G998B Not Recognized by Odin:
- Reinstall the Samsung USB drivers and ensure the phone is actually in Download Mode. Swap out your USB cable for a higher quality one, as Odin is notoriously picky about cable integrity.
- KG Lock / Knox Triggered After Flashing:
- This security measure activates if a Samsung account remained logged in before the flash, or if unofficial software was applied. Always log out of Samsung accounts beforehand. Once KG lock is active, you typically need a professional tool to remove it.
- Boot Loop After Flashing:
- Open recovery mode (Volume Up + Power) and perform a factory reset. This wipes out conflicting data left behind by the previous operating system.
Frequently Asked Questions
Q1: Will flashing the Samsung Galaxy S21 Ultra 5G SM-G998B firmware erase my data?
A: Yes. Using Odin to install this firmware resets the phone to its factory defaults, including the base Android 15, One UI settings. Every app, photo, contact, and account will be deleted. Save anything important beforehand, because data recovery is impossible after the flash finishes.
Q2: Is this firmware compatible with other Samsung models?
A: No. This specific firmware is designed exclusively for the Samsung Galaxy S21 Ultra 5G SM-G998B utilizing the Exynos 2100 (5 nm) processor. Even a slightly different variant of the SM-G998B might use entirely different internal hardware. Installing the wrong software will severely damage the phone. Always double-check your exact model in Settings › About Phone.
Q3: Can I downgrade from the latest version to an older firmware version?
A: While technically possible on certain Exynos builds, rolling back is highly discouraged. Downgrading introduces security vulnerabilities and application instability on Android 15, One UI. If the newest update is causing problems, leave a comment below, as there is likely a better solution than a downgrade.
Q4: What should I do if I encounter an FRP lock after flashing?
A: Download our free Android apps launcher. FRP activates on the Samsung Galaxy S21 Ultra 5G SM-G998B when a Google account remains logged in prior to flashing. Removing your Google account beforehand prevents this hurdle completely.
Q5: Are custom ROM options available for the Samsung Galaxy S21 Ultra 5G SM-G998B?
A: This page focuses entirely on official Samsung stock software. Whether custom ROMs exist for the Samsung Galaxy S21 Ultra 5G SM-G998B depends on the open-source kernel availability for the Exynos 2100 (5 nm) chip. Visit our Custom ROMs page or browse the XDA Developers forum for specific custom development threads.
Q6: My Samsung Galaxy S21 Ultra 5G SM-G998B is not detected by Odin. What should I do?
A: Start by reinstalling the Samsung USB drivers and rebooting your computer. Try moving the cable to a USB 2.0 port instead of USB 3.0, as Samsung phones communicate more reliably over USB 2.0. Temporarily disable your antivirus software. If the issue persists, leave a comment with the exact error message for further assistance.
Q7: How do I enter recovery mode on my Samsung Galaxy S21 Ultra 5G SM-G998B?
A: Turn the phone off entirely, then press Volume Up + Power together until the recovery menu appears. On older Samsung devices featuring a physical Home button, press Volume Up + Home + Power. The recovery screen displays the current build number for your Samsung Galaxy S21 Ultra 5G SM-G998B, which helps verify your software version.
Q8: My IMEI shows “unknown” after flashing the Samsung Galaxy S21 Ultra 5G SM-G998B. Is my phone permanently damaged?
A: No, the phone is not permanently broken, although the error looks intimidating. Follow the IMEI repair guide located in the troubleshooting section. For Samsung handsets, EFS partition corruption is the usual culprit. Do not insert a SIM card until the IMEI is successfully restored.
Q9: How long does it take to flash Samsung Galaxy S21 Ultra 5G SM-G998B firmware?
A: The Odin flashing procedure generally requires 3 to 10 minutes, depending on the file size and your USB transfer speeds. The first reboot after the flash takes an additional 3 to 8 minutes. Never interrupt the phone during either phase. If the Odin progress bar stalls, wait a few extra minutes before assuming the process failed.
Final Thoughts on Samsung Galaxy S21 Ultra 5G SM-G998B Firmware
The Samsung Galaxy S21 Ultra 5G SM-G998B firmware installation is a straightforward process that will completely restore your device when followed correctly. That covers the entire procedure for safely flashing the official software (the latest version) via Odin. If you followed the instructions closely, your phone should now operate on a clean, stable software build.
If you ran into an error or a specific step failed, drop a comment below. Include the exact error message, the step you are currently on, and the troubleshooting steps you have already attempted. I review every comment and will help you resolve the issue.
If this tutorial got your phone working again, please share it to help others facing the same software problems.
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.
