Samsung Galaxy A42 5G (SM-A426U1) - ATT - A426U1UEU1AUD4 firmware
Samsung Galaxy A42 5G firmware A426U1UEU1AUD4 is the Android 11 build for the Samsung Galaxy A42 5G (model SM-A426U1), released by Samsung for USA (AT&T) (ATT). It was built on 9 April 2021, carries the 2021-04-01 Android security patch, has changelist 21186233. The package combines system build A426U1UEU1AUD4 (AP/PDA) with CSC build A426U1OYM1AUD4 for the ATT region code. The download is 4.8 GB and has MD5 checksum 698b8c0dee12227a8807e3b91f3e617f, so you can verify the file after downloading. SamMobile added this file to the firmware archive on 9 April 2021.
How to flash A426U1UEU1AUD4 on the Samsung Galaxy A42 5G (SM-A426U1)
We recommend updating through Samsung's own tools: over-the-air (Settings › Software update) or Samsung Smart Switch on a PC. Flash the full firmware with Odin only when you are sure about the risks. A wrong region or a failed flash can brick the device, and SamMobile is not responsible for any damage.
- Download the firmware package above and extract the ZIP. It contains the AP (PDA), BL, CP and CSC files, plus a HOME_CSC file.
- Download and extract Odin on a Windows PC, and install the Samsung USB drivers if the PC does not detect the phone.
- Switch the device off and boot it into Download mode (usually Volume Up + Volume Down while connecting the USB cable, or Volume Down + Bixby + Power on older models).
- Open Odin. The ID:COM box turns blue when the device is connected.
- Load the files in their slots: BL, AP, CP and CSC. Use HOME_CSC to keep your apps and data, CSC to wipe the device.
- Leave Re-Partition unticked and click Start. The device reboots when Odin shows PASS. The first boot after a flash can take a few minutes.
Step-by-step PDFs: 5-file firmware and 1-file firmware.
What the build numbers mean
PDA / AP (A426U1UEU1AUD4) is the Android system build; its last three characters encode the year, month and revision. CSC (A426U1OYM1AUD4) is the region and carrier configuration, and CP is the modem firmware. The product code ATT identifies the region or carrier this package was made for ( USA (AT&T)); our list of Samsung CSC codes maps every code to its country and carrier. Flashing a package for a different product code changes carrier features and can be refused by the bootloader, so pick the one that matches the CSC shown under Settings › About phone › Software information.