G991USQSJHZB1 – Galaxy S21 5G firmware

Build G991USQSJHZB1 is a security update for the Galaxy S21 5G (SM-G991U) on Android 15 (One UI 7). It first appeared on Samsung's servers on Mar 17, 2026 (method) and has reached 8 regions so far. It keeps bootloader bit 19, so downgrading to the previous build G991USQSJHZAA is still possible. Samsung still serves this file.

Model
SM-G991U
Android
Android 15
Type
Security
Bootloader bit
19
First released
Mar 17, 2026
Regions
8

Rollout timeline by region

The date each region code (CSC) first received G991USQSJHZB1, counted from the first release.

CSCRegionReleasedRolloutVersion (PDA/CSC/MODEM)
ATTUSA (AT&T)Mar 17, 2026day 0G991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
CCTUSA (Comcast)Mar 18, 2026+1 dayG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
SPRUSA (Sprint)Mar 18, 2026+1 dayG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
TMBUSA (T-Mobile)Mar 18, 2026+1 dayG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
DSHUSAMar 19, 2026+2 daysG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
DSAUSAMar 19, 2026+2 daysG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
VZWUSA (Verizon)Mar 22, 2026+5 daysG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1
USCUSA (US Cellular)Mar 25, 2026+8 daysG991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1

Download and release notes

samloader download -m SM-G991U -r ATT -v G991USQSJHZB1/G991UOYNJHZB1/G991USQSJHZB1

Samsung's release notes and security patch level for this update: SM-G991U / ATT on doc.samsungmobile.com. What each part of the build number means: decode G991USQSJHZB1.