G991USQSJHZAA – Galaxy S21 5G firmware
Build G991USQSJHZAA 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 Jan 28, 2026 (method) and has reached
8 regions so far. It raises the bootloader bit from 18 to 19: once installed, the device no longer accepts firmware with bit 18 or lower, so a downgrade to G991USQSIHYL1 is blocked. Samsung still serves this file.
- Model
- SM-G991U
- Android
- Android 15
- Type
- Security
- Bootloader bit
- 19
- First released
- Jan 28, 2026
- Regions
- 8
Rollout timeline by region
The date each region code (CSC) first received G991USQSJHZAA, counted from the first release.
| CSC | Region | Released | Rollout | Version (PDA/CSC/MODEM) |
|---|---|---|---|---|
DSA | USA | Jan 28, 2026 | day 0 | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
DSH | USA | Jan 28, 2026 | day 0 | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
CCT | USA (Comcast) | Jan 28, 2026 | day 0 | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
SPR | USA (Sprint) | Jan 29, 2026 | +1 day | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
TMB | USA (T-Mobile) | Jan 29, 2026 | +1 day | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
ATT | USA (AT&T) | Feb 1, 2026 | +4 days | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
VZW | USA (Verizon) | Feb 1, 2026 | +4 days | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
USC | USA (US Cellular) | Feb 3, 2026 | +6 days | G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAA |
Download and release notes
samloader download -m SM-G991U -r DSA -v G991USQSJHZAA/G991UOYNJHZAA/G991USQSJHZAASamsung's release notes and security patch level for this update: SM-G991U / DSA on doc.samsungmobile.com. What each part of the build number means: decode G991USQSJHZAA.