A566U1UESACZHB – Galaxy A56 5G firmware

Build A566U1UESACZHB is a security update for the Galaxy A56 5G (SM-A566U1) on Android 16 (One UI 8). It first appeared on Samsung's servers on Sep 1, 2026 (method) and has reached 11 regions so far. It raises the bootloader bit from 9 to 10: once installed, the device no longer accepts firmware with bit 9 or lower, so a downgrade to A566U1UES9CZG7 is blocked. Samsung still serves this file.

Model
SM-A566U1
Android
Android 16
Type
Security
Bootloader bit
10
First released
Sep 1, 2026
Regions
11

Rollout timeline by region

The date each region code (CSC) first received A566U1UESACZHB, counted from the first release.

CSCRegionReleasedRolloutVersion (PDA/CSC/MODEM)
ACGUSA (C Spire)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
AIOUSA (Cricket)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
ATTUSA (AT&T)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
CCTUSA (Comcast)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
LRAUSA (Bluegrass)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
TMBUSA (T-Mobile)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
TMKUSA (MetroPCS)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
USCUSA (US Cellular)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
VZWUSA (Verizon)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
XAAUSA (unlocked)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB
XARUSA (Cellular South)Sep 1, 2026day 0A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB

Download and release notes

samloader download -m SM-A566U1 -r XAA -v A566U1UESACZHB/A566U1OYMACZHB/A566U1UESACZHB

Samsung's release notes and security patch level for this update: SM-A566U1 / XAA on doc.samsungmobile.com. What each part of the build number means: decode A566U1UESACZHB.