How To Guide G998U and G998U1 Firmware Links and Flashing Discussion Here

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maddoggin

Senior Member
Jul 6, 2010
2,803
3,050
corpus christ
Anyone know if SM-G998U1/XAA will get ukf or uk9 update? I'm currently on uk7 but I see tmo and other carriers already got ukf wondering if there's an eta for G998U1 update
 

readymarc

Senior Member
Dec 30, 2016
193
50
U1 Unlocked is out now
Screenshot_20211207-050344_Software update.jpg
 

dcfjoe

Senior Member
Jul 8, 2013
149
42
Like posted above, I just got the OTA notification on my unlocked S21 Ultra on the Visible network.

It installs the BUKF build and is still on the November security update.

However, it fixes the extremely annoying 120 Hz bug that was present in BUK7. I have been using the Show Refresh Rate toggle found in the Dev Options, and I can verify that the phone stays at 120 Hz when scrolling even after your finger has stopped touching the screen. It does of course revert to 60 Hz after a while, but that's way after the scrolling animation is complete.

Edit: Snapchat is still wonky in that it decides when it wants to be 120 or 60 Hz, but that's how that app has always been.
 

TheAnarchi1

Member
Nov 28, 2014
11
6
Samsung Galaxy S21 Ultra
Like posted above, I just got the OTA notification on my unlocked S21 Ultra on the Visible network.

It installs the BUKF build and is still on the November security update.

However, it fixes the extremely annoying 120 Hz bug that was present in BUK7. I have been using the Show Refresh Rate toggle found in the Dev Options, and I can verify that the phone stays at 120 Hz when scrolling even after your finger has stopped touching the screen. It does of course revert to 60 Hz after a while, but that's way after the scrolling animation is complete.

Edit: Snapchat is still wonky in that it decides when it wants to be 120 or 60 Hz, but that's how that app has always been.

I agree that this build seems to have greatly improved the Adaptive Refresh function. The situation still isn't perfect but that could be more the nuances of different apps than Samsung's UI. The only thing I see that need cleaning up now are the notification shade animations (still a tad janky even when on 120hz).

However, (and this might affect others) after installing the OTA I needed to wipe the cache in recovery for the Adaptive Refresh setting to sort itself out. If any are still having issues after the update then WIPE YOUR CACHE.

PS: Did you know that the panel stays fixed at 120hz when connected to a power source? For some reason I only discovered that today when I had the refresh developer setting activated to check out the Adaptive Refresh situation in this new build!
 

carlossantana05

Senior Member
Feb 6, 2016
190
15
@iBowToAndroid

which CSC brings the anti-spam in the calls? I mean daughter. I am going to buy the 998u and I will put the 998u1 with the CSC XXA, I only have to update by odin or do I have to do something additional to do that update. someone who has done it.
 

iBowToAndroid

Senior Member
Nov 9, 2010
5,112
1
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Twin Cities MN
@iBowToAndroid

which CSC brings the anti-spam in the calls? I mean daughter. I am going to buy the 998u and I will put the 998u1 with the CSC XXA, I only have to update by odin or do I have to do something additional to do that update. someone who has done it.
As far as I know, that's a carrier feature, not a CSC one. It's provided by your wireless network, not Samsung
 

cfranko

New member
Jan 21, 2022
4
0
I have a ATT Unlocked SM-G998U, I want to get rid of bloatware and update to Android 12. Can I directly flash the Android 12 version of SM-G998U1 using Odin without issues?
 

V0latyle

Forum Moderator
Staff member
You never need to unlock the bootloader of any device, from any manufacturer, in order to flash official manufacturer firmware.

Yes, modded Odin is always required
Not entirely correct. On the Pixel series, an unlocked bootloader is required to flash the official manufacturer firmware. The only update that is possible with a locked bootloader, at least on Pixels, is OTA, whether automatic or sideload.

Granted, this isn't relevant to Samsung devices, but what's true for Samsung is not necessarily true for other OEMs.
 

carlossantana05

Senior Member
Feb 6, 2016
190
15
As far as I know, that's a carrier feature, not a CSC one. It's provided by your wireless network, not Samsung
Thanks for your answer, but you helped me with a decision, I'm from the Dominican Republic, I got the SM-G998U1 and I want a clean firmware that updates quickly, which firmware would you recommend for flashing? I ask you why you have more experience, I come from the s20+. Thank you
 

iBowToAndroid

Senior Member
Nov 9, 2010
5,112
1
1,628
Twin Cities MN
Thanks for your answer, but you helped me with a decision, I'm from the Dominican Republic, I got the SM-G998U1 and I want a clean firmware that updates quickly, which firmware would you recommend for flashing? I ask you why you have more experience, I come from the s20+. Thank you
Firmware ending in U1 is the only "clean" version that exists. So you should stay with what you have
 

dpw2atox

Senior Member
Mar 25, 2010
320
51
I've had the update installed a few days now, havent noticed much of a difference honestly. Still not as good though as battery life was under Android 11 and One UI 3.1.1.
 

mapl.ph

Senior Member
Feb 18, 2012
149
6
PH
Samsung Galaxy S21 Ultra
Hi All,

Recently flashed mine to SM-G998U1/XAA , which I think is an AT&T version. I would like to confirm what 5G bands does it support? Does changing back to SM-G998U gives me different bands or not? Thanks.
 

iBowToAndroid

Senior Member
Nov 9, 2010
5,112
1
1,628
Twin Cities MN
Hi All,

Recently flashed mine to SM-G998U1/XAA , which I think is an AT&T version. I would like to confirm what 5G bands does it support? Does changing back to SM-G998U gives me different bands or not? Thanks.
No, that's not an AT&T version. All bands should be enabled in all firmwares, but whatever your Service Provider SW is set to is probably what determines priority
 

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    For those who aren't already aware, G998U is the model number of all of the US carrier versions of the S21 Ultra. The G998U1 is the model number of the same device, but sold by Samsung SIM unlocked and with no carrier bloatware. Firmware is 100% interchangeable among these models: any U or U1 firmware version can be flashed to any U or U1 device at any time, assuming that you're not trying to downgrade the bootloader. A "U to U" or "U1 to U1" flash does not require a factory reset, but changing from one firmware to the other will require one. Also, U firmware is identical for the 4 base files (AP, BL, CP, CSC) for each individual build, no matter which carrier it comes from. So if you download 2 different carrier versions of the exact same build, the 4 base files will be identical. Where the firmware differs is in the USERDATA file - that's where the carrier bloatware and customizations reside.

    Manual Odin flashing is designed for those who:

    - want to manually update to a newer version of U firmware on their U device, either because they don't want to wait for their carrier's OTA or because OTAs aren't working on their device, or a different carrier got a new feature/patch before they did
    - want to flash U1 firmware to their U device
    - want to convert from U1 firmware to carrier U firmware
    - want to convert from one carrier's U firmware (with all apps and bloatware) to a different carrier's U firmware (with all apps and bloatware)

    For those who aren't already aware, anyone can now download firmware for almost any Samsung device any time that they want, via the various firmware download tools posted here on XDA like SamFirm or Frija. There are threads and info about them here on XDA so I won't waste time explaining - do a search if you're not already familiar with these tools. But they only provide whatever the latest/newest/current version is - nothing older. I pay for a subscription to a site that gets the official releases (usually) before they hit the firmware download tools, so that's where my files come from.

    This is not a "beginner's guide to Odin flashing" -type post/thread, so I won't list basic, step-by-step flashing instructions. My threads are geared towards those who already know what they're doing. If you're new to manually flashing Samsung firmware (or haven't done it in a long time), I recommend you consult one of those "beginner's" guides- there are tons of them here on XDA.

    Happy flashing!

    U firmware: https://www.androidfilehost.com/?w=files&flid=322089
    U1 firmware: https://www.androidfilehost.com/?w=files&flid=322090

    Notes:

    - DON'T QUOTE THE OP WHEN YOU REPLY, kthx

    - I have lots of threads just like this one for other Samsung flagships, if it interests you. For those who have already made use of my previous threads for a different device and are upgrading to an S21, welcome back :)

    - My zips are compressed extra small for space and bandwidth savings. The default Windows extractor can't handle it, so you'll need a 3rd party tool like 7zip, WinRAR, etc

    - it's quite time consuming to download the files, zip them up, and upload them to AFH. And, I do threads like this for every single Sx and Note x model, so I won't be uploading every single version. The only full builds that I upload are ones where I get access to a new bootloader and/or Android version early, before they hit the firmware download tools.

    - My naming method for folders on AFH is: build - bootloader - Android version
    So "SAT - 1 - 9.0" means the full build number ends in SAT, it's bootloader version 1, and it's Android 9.0. When bootloader and Android versions increment, the first build to have those changes will have its folder notated appropriately.

    - HOME CSC file keeps data intact; using the other CSC will wipe data. Flashing USERDATA will also wipe data.

    - Since AT&T doesn't allow their firmware to be publicly available (for any of their devices), I'll try to always upload at least one USERDATA per bootloader increment for AT&T (and Cricket, if they get this model). I'll also upload any full builds if AT&T is the only carrier to get that specific build, because you won't be able to find the files anywhere else.

    - For identifying USERDATAS, and to know what region/CSC to use in the firmware download tools if you're downloading yourself:

    AIO = Cricket (not available via firmware download tools)
    ATT = AT&T (not available via firmware download tools)
    BST = Boost Mobile
    CCT = Xfinity Mobile (Comcast)
    CHA = Spectrum Mobile (Charter)
    DSH = Dish Network
    SPR = Sprint
    TMB = T-Mobile
    TMK = Metro PCS
    USC = US Cellular
    VZW = Verizon (available via firmware download tools, but Manual Entry is required - Auto will not work)
    XAA = U1 firmware

    - the correct procedure for switching from one carrier's firmware to another carrier's firmware is:
    1. Flash full U1 firmware package including non HOME CSC
    2. Upon boot, insert a SIM of the carrier whose firmware you want
    3. Watch for the popup that says "reboot to apply new carrier settings" etc, and do it
    4. After that restart completes, reboot back to Download mode and flash the full U firmware package, with the USERDATA file of the carrier whose firmware you want
    2
    Initial U firmware and AT&T USERDATA are posted, along with U1 firmware. U firmware is not yet accessible in the firmware download tools like SamFirm and Frija, but if anyone wants a different carrier's USERDATA (for flashing bloatware to a U1 device or for converting a U device from one carrier's bloatware to a different one), let me know and I'll get it for you
    2
    I've seen nothing about the May update for the G998U1. Older phones are getting it but we haven't.
    2
    Have the Verizon version, what is the benefits of flashing to U1?
    The only benefits I can think of would be enabling Samsung features that Verizon disables, like the Spam Filter, and removing some of the bloat that might be impossible to remove on the VZ version.
    2
    I would think you would have most features since the U1 firmware is sold by Samsung to work on networks like T-Mobile. However, all I can verify for you is that I got my wifi calling and I have a 5G icon with 305Mb on speed test. This is after flashing U1.

    I had the same issue. Out of the box, without even turning the phone on, I flashed the U1 firmware on my T-mobile S21 ultra but the device just kept saying "NO SIM"

    If you have a T-mobile device, turn it on with an active sim card first with the original U firmware. Don't need to go through the setup, just have to let it find a LTE/5G signal. After that you can power down and flash U1 firmware and won't have any SIM issues.

    Hope this might help anyone who might run into the same issues we did