Last Updated: June 3, 2026
The Snapdragon 888 inside the SM-G991W is a fantastic 5nm chip, but even powerful hardware occasionally needs a clean software install. If you need to restore your phone, this page has the official Samsung Galaxy S21 5G SM-G991W firmware, along with all the necessary drivers, tools, and step-by-step instructions.
Device: Samsung Galaxy S21 5G SM-G991W | Chipset: Qualcomm SM8350 Snapdragon 888 5G | Flash Tool: Odin
Android: Android 11, One UI 3.1 | File Type: .tar.md5 / ZIP (Contains AP, BL, CP, CSC files for Odin)
⚠ Warning: Flashing erases all data. Back up first.
Samsung Galaxy S21 5G SM-G991W Firmware (Flash File) Drivers, Tools & Guide
Installing the official software package using Odin is the most reliable way to fix software bugs and restore your device to factory settings. I have organized everything you need right here, including the correct Odin version and the matching Samsung Galaxy S21 5G SM-G991W firmware files.
Before you connect your phone, sign out of your Samsung account. Skipping this step will trigger Knox security, which takes extra effort to unlock. Samsung packages arrive as ZIP files containing .tar.md5 components. After extracting, look for AP_, BL_, CP_, and CSC_ files. If those are missing, the package is incorrect for your phone.
Use WinRAR or 7-Zip to unpack your download. Once extracted, verify that you see files named AP_*.tar.md5, BL_*.tar.md5, CP_*.tar.md5, and CSC_*.tar.md5 (or HOME_CSC_*.tar.md5). If you do not see these specific files, you might have downloaded the wrong package.
Remember that installing stock software wipes your internal storage completely. This is exactly what resolves persistent glitches, FRP locks, sluggish performance, forgotten passwords, bootloops, connectivity drops, and soft brick situations.
Hard Reset Samsung Galaxy S21 5G SM-G991W
A hard reset restores the phone to its original factory state by wiping all user data through the recovery menu. To do this without a computer, turn off the handset completely, then press and hold Volume Up + Power (use Volume Up + Home + Power on older models) until the recovery screen loads. Highlight “Wipe Data/Factory Reset” using the volume rocker and press Power to confirm.
This process clears out the internal storage and returns the Samsung Galaxy S21 5G SM-G991W to its out-of-the-box state. It fixes common complaints like random crashes, lagging, and forgotten screen locks. If the problem continues after the wipe, a full Odin flash is the next step.
Samsung Galaxy S21 5G SM-G991W FRP Bypass
Factory Reset Protection (FRP) triggers when a Google account is left signed in before a wipe, requiring a specific bypass method to regain access. You can use our free Android apps launcher to access settings during the setup wizard and remove the lock. Removing your Google account before wiping prevents this entirely.
Why Do We Need Samsung Galaxy S21 5G SM-G991W Firmware?
Flashing the official stock ROM is necessary to resolve severe software corruption, update the operating system, or remove malicious locks. The Samsung Galaxy S21 5G SM-G991W uses Odin for this process, which handles everything from minor updates to major recoveries:
- Regain access if the handset is locked or disabled.
- Upgrade to the newest Android release supported by the hardware.
- Eliminate freezing, lag, and continuous bootloops on your SM-G991W.
- Fix battery drain and failed over-the-air updates.
- Return to the original factory state to maintain warranty validity.
- Repair a system that will only boot into the recovery environment.
- Clear KG state or Knox errors resulting from a bad or interrupted flash.
Learn more about stock ROMs and why flashing works.
Choosing the Right Firmware Version
Selecting the correct file requires matching your exact model number, region code, and binary level to avoid damaging your phone. Double-checking these details prevents major headaches:
- Identify Your Exact Model Number: Open Settings › About Phone and read the full model name (e.g. SM-G991W). The final letter indicates the region, U/U1 is USA, W is Canada, N is Korea, and B/F is Global. Installing a file meant for another region will cause errors.
- Match the CSC (Region): The 3-letter region code in the file name must align with your phone. Find your current CSC under Settings › About Phone › Software Information, or read the Service Provider line in Download Mode. Examples include XAA (US), BTU (UK), INS (India), and SER (Russia).
- Check the Binary Level: Read the version string on your phone (e.g.
XXU9BZDP, the digit after the letters is the binary level). Downgrading to a lower binary is blocked by the bootloader. If you are on Binary 9, you must install Binary 9 or newer. - Confirm the Build Date: The final 4 characters of the PDA string represent the build date. The first letter is the year (A=2024, B=2025, C=2026), and the second is the month (A=Jan through L=Dec).
- Verify in Download Mode: Power down, then press Volume Down + Power to reach Download Mode. This menu displays your exact model, CSC, and software version for easy verification.
Firmware Details for Samsung Galaxy S21 5G SM-G991W
The official package includes the necessary AP, BL, CP, and CSC files formatted for Odin. Here are the exact specifications for this release:
| Firmware Information | Details |
|---|---|
| Device Model | Samsung Galaxy S21 5G SM-G991W |
| Firmware Version | G991WVLU9FWK5 |
| File Size | 7.4 GB |
| Android Version | Android 11, One UI 3.1 |
| Platform | Qualcomm SM8350 Snapdragon 888 5G |
| Release Date | Released 2021, January 29 |
| Region | SM |
| File Type | .tar.md5 / ZIP (Contains AP, BL, CP, CSC files for Odin) |
Which Firmware Version Should I Download?
Choosing the right build depends on your specific issue, such as a stuck logo or an FRP lock. Find your scenario in the table below to get the correct file:
| Your Situation | What I Recommend |
|---|---|
| Phone is completely dead or stuck on logo | G991WVLU9FWK5, download this one. It is the latest Samsung Galaxy S21 5G SM-G991W 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 G991WVLU9FWK5 first, then follow the IMEI repair guide. Do not skip the reflash. |
| G991WVLU9FWK5 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 | G991WVLU9FWK5, 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 5G SM-G991W Firmware
You can grab the official G991WVLU9FWK5 build directly from the links provided below. Always check that the file size matches the details above to ensure the download is not corrupted, as installing a broken file creates more problems.
| Software Details | Download Link | Members Link |
|---|---|---|
|
File Name: SM-G991W_G991WVLU9FWK5_G991WOYV9FWK5_BMC_4file.zip Size: 7.4 GB | Download Link | Download Link2 |
Only download software 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-G991W with a different letter suffix. Check About Phone carefully, one letter difference can cause a failed or broken flash.
- Your chipset differs from Qualcomm SM8350 Snapdragon 888 5G. 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 5G SM-G991W Firmware
Preparing your computer and phone before opening Odin prevents common errors like dropped connections or security locks. Two frequent culprits are unsigned Samsung accounts and low-quality USB cables. Always use a high-quality data cable to maintain a stable connection throughout the 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 5G SM-G991W
The installation process uses Odin to load the AP, BL, CP, and CSC files onto your device in Download Mode. Ensure “Auto Reboot” and “F. Reset Time” are checked for the best results. If you are not sure which Odin version to use, check our Odin versions page. Some older Samsung devices work better with 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 5G SM-G991W Firmware
A successful flash results in a PASS message in Odin and a longer initial boot time as the system configures itself. Here is what is completely normal after installing the Samsung Galaxy S21 5G SM-G991W firmware:
- How to know the flash was successful: Odin will display “PASS.” in a green box near the top of the window. Seeing this means the installation finished properly.
- First boot takes 3 to 8 minutes, give the phone time to optimize its apps. Forcing a restart during this stage can cause system corruption.
- The phone will feel warm during first boot, the processor is working hard to initialize the new system. It will cool down shortly.
- All your apps are gone, a clean install removes all third-party applications. You will need to redownload them from the Play Store.
- Dial *#06# immediately after setup to verify your IMEI status. Do this before inserting a SIM card. If the screen reads “unknown”, check the IMEI repair guide right away.
- Be careful when re-adding your Google account, entering your credentials during the initial setup wizard is the safest route to avoid triggering FRP.
- Wi-Fi, Bluetooth, and mobile data should connect automatically. If mobile data fails, navigate to Settings › SIM and Network to manually input your carrier APN details.
- Stuck in a bootloop after first boot? Boot into recovery and execute a factory reset, see the hard reset guide above. This clears out conflicting temporary files from the previous installation.
- Samsung Smart Switch: After flashing your Samsung Galaxy S21 5G SM-G991W firmware, Samsung Smart Switch may prompt you to install additional updates. Let it complete, this ensures your device has the latest security patches for your region.
Missing IMEI or Corrupt Baseband on Samsung Galaxy S21 5G SM-G991W After Flashing?
A missing baseband or null IMEI usually indicates a corrupted EFS partition that requires dedicated repair tools to restore. Keep in mind that writing a fake IMEI is illegal in many regions, so only restore the original number assigned to your phone. Programs like ChimeraTool or BFT are capable of fixing this. Verify your local regulations before proceeding.
Video Guide: How to repair IMEI
Common Issues When Flashing Samsung Galaxy S21 5G SM-G991W
- Odin Shows “FAIL” Instead of “PASS”:
- This typically means the region or model of the file does not match your hardware. Double-check your exact model number in Settings › About Phone. Even a single letter mismatch will cause a failure.
- Samsung Galaxy S21 5G SM-G991W Not Recognized by Odin:
- Reinstall the Samsung USB drivers and confirm the phone is actually in Download Mode. Swapping to a different, high-quality data cable often resolves detection issues.
- KG Lock / Knox Triggered After Flashing:
- This security measure activates if a Samsung account remained logged in prior to the flash, or if non-official software was applied. Removing accounts beforehand prevents this. Resolving an active KG state usually requires a professional service tool.
- Boot Loop After Flashing:
- Access the recovery menu (Volume Up + Power) and perform a wipe data factory reset. This clears out lingering files from the previous installation that are causing conflicts.
Frequently Asked Questions
Q1: Will flashing the Samsung Galaxy S21 5G SM-G991W firmware erase my data?
A: Yes. Running this installation through Odin formats the internal storage and applies the default Android 11, One UI 3.1 settings. Every app, photo, contact, and account will be permanently deleted. Save anything important beforehand, as there is no method to recover files once the process finishes.
Q2: Is this firmware compatible with other Samsung models?
A: No. This specific build is designed exclusively for the Samsung Galaxy S21 5G SM-G991W equipped with the Qualcomm SM8350 Snapdragon 888 5G processor. Even a slightly different variant of the SM-G991W might utilize entirely different internal hardware. Loading the incorrect package can severely damage the phone. Always verify your exact model in Settings › About Phone.
Q3: Can I downgrade from G991WVLU9FWK5 to an older firmware version?
A: While occasionally possible on Qualcomm platforms, rolling back is generally not advised. Downgrading can introduce security vulnerabilities and app instability on Android 11, One UI 3.1. If G991WVLU9FWK5 is giving you errors, leave a comment below, there is usually a safer alternative to reverting.
Q4: What should I do if I encounter an FRP lock after flashing?
A: Grab our free Android apps launcher. The FRP prompt on the Samsung Galaxy S21 5G SM-G991W appears when a Google profile remains signed in before wiping. Logging out of your Google account prior to flashing is the easiest way to bypass this headache.
Q5: Are custom ROM options available for the Samsung Galaxy S21 5G SM-G991W?
A: This tutorial focuses entirely on official Samsung stock software. The availability of aftermarket ROMs for the Samsung Galaxy S21 5G SM-G991W relies on whether developers release open-source kernels for the Qualcomm SM8350 Snapdragon 888 5G. Visit our Custom ROMs page or browse the XDA Developers forum for community-built projects.
Q6: My Samsung Galaxy S21 5G SM-G991W is not detected by Odin. What should I do?
A: Driver issues are usually the cause. Reinstall the Samsung USB drivers, reboot your computer, and try again. Moving the cable to a USB 2.0 port often helps, as Samsung handsets sometimes struggle with USB 3.0 connections. Temporarily disable your antivirus software. If it still fails, drop a comment with the exact error message and I will assist you.
Q7: How do I enter recovery mode on my Samsung Galaxy S21 5G SM-G991W?
A: Shut the phone down entirely, then press Volume Up + Power simultaneously until the recovery menu pops up. If you are using an older Samsung with a physical Home key, press Volume Up + Home + Power. The recovery screen lists the active build number for your Samsung Galaxy S21 5G SM-G991W, which is helpful for confirming your current software version.
Q8: My IMEI shows “unknown” after flashing the Samsung Galaxy S21 5G SM-G991W. Is my phone permanently damaged?
A: No, the hardware is perfectly fine. This is a software glitch that you can fix. Read the IMEI repair guide located in the troubleshooting section. For Samsung phones, EFS partition corruption is the primary suspect. Just 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 5G SM-G991W firmware?
A: The Odin transfer generally requires 3 to 10 minutes, depending on the total file size and your USB transfer speeds. The initial reboot afterward takes an additional 3 to 8 minutes. Never unplug the device during either phase. If the Odin progress bar seems frozen, wait a few extra minutes before troubleshooting.
Final Thoughts on Samsung Galaxy S21 5G SM-G991W Firmware
Following these steps will successfully restore your phone to a clean, functional state using the official G991WVLU9FWK5 build. If you followed the instructions carefully, your handset should now be running smoothly on a fresh system.
If you ran into an unexpected error or a specific step did not work, leave a comment below. Include the exact error message, the step you are stuck on, and the troubleshooting steps you have already attempted. I read every comment and will help you resolve the issue.
If this tutorial helped you get your phone back online, please consider sharing it. Sharing is a great way to help others facing the exact same situation.
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.
