Galaxy S21 SM-G991U U4 Firmware – Android 11 R

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S21 SM-G991U Binary 4 Firmware

The specific Galaxy S21 SM-G991U U4 Firmware Download Package comes with a Stock ROM of Galaxy S21 SM-G991U U4 Security Patch Level 2021-10-01 (October 1, 2021). This helps bypass the FRP lock and revert from the root and custom ROM.

Samsung Galaxy S21 SM-G991U Binary 4 Android 11 R United States USC G991USQS4AUIN

There are various reasons to flash “Stock Firmware on Galaxy S21 SM-G991U U4“. For instance, if your phone gets stuck on the logo and you need to remove the FRP lock from it.

The Advantages Of Stock ROM:

  • Fix boot loop issue
  • Update and Downgrade
  • Unroot or Fix Bugs
  • To solve the lag or stutter
  • Fix software issues.
  • Revert to stock firmware


Galaxy S21 SM-G991U U4 Stock ROM Details:

SM-G991U U4 United States USC G991USQS4AUIN:

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Model SM-G991U Binary 4 U4, S4, Bit 4
Region / Country United States / USA
Language Multi-Language / Language
Android version Android 11 R
Operator / Carrier Clean USC (no logo, carrier apps)
product code USC
Build Date 28 Sep 2021
Security Patch Level 2021-10-01 (October 1, 2021)
Size 6.4 GB
[quads id=2]
Download Google Drive Android File Host

How To Install Galaxy S21 SM-G991U U4 Stock Firmware:

1: Download and Install the Samsung USB Driver on your computer. If a Samsung USB Driver is installed on your computer, then Skip this Step.

2: Download and extract the Galaxy S21 SM-G991U U4 Firmware files on your computer.

3: Now, Switch off your Smartphone.

4: Turn off the phone and boot into Download Mode.

Press and hold Volume Down, Home and Power button at the same time for 5-8 seconds until download mode is active.

5: A Warning Yellow Triangle Sign appears in Download mode. Press the Volume Up key to proceed.

6: Open Odin. Then, connect your phone to the pc.

7: Odin will detect the device and show the “Added message in the lower-left panel.”.

8: Click the PDA button and select the Firmware.tar file.

9: Now, click the Start button in Odin to begin the Flashing.

10: Flashing usually takes 30-50 seconds to complete on your Phone.

Once you spot the “Pass” message in Odin, you can unplug your device from the computer.

You should run your desired firmware when your Galaxy S21 SM-G991U U4 finally boots up.

To verify the installed firmware, go to Settings → About Phone → Software Information. Check the firmware number under Baseband version.


  • Read and understand the Full Guide before flashing.”Galaxy S21 SM-G991U U4 Firmware.
  • Use these instructions at your own risk. We are not liable for any outcomes on your device due to following the information in this guide.
  • Phone must have a 70–80% charge.
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