A combination file (also called combination firmware or factory binary) is a special engineering firmware used by Samsung for factory testing and diagnostics. It is not a regular stock ROM — it is a stripped-down version of the operating system that gives access to hardware testing, service menus, and bypasses certain security features including FRP.
What is a Combination File?
Samsung's combination firmware is used in their factories and service centers to test hardware components before the device ships. Key characteristics:
- No Google services — no Play Store, no Google apps, no FRP
- Service mode access — hardware diagnostic menus for testing display, touch, sensors, cameras, speakers, microphones
- ADB root access — the combination firmware runs with root by default, allowing shell access to the file system
- No Knox enforcement — Knox security checks are disabled
- No OTA updates — the device will not try to update itself
Combination files are identified by their filename format: COMBINATION_FAC_FAS26_S938BXXU1AXA1.zip
When to Use a Combination File
FRP Bypass: Since combination firmware has no Google services, flashing it removes the FRP lock. After booting into the combination firmware, you can access the device without any Google account verification. Then flash stock firmware to return to normal.
Hardware Diagnostics: Test individual components — screen burn-in check, touch accuracy, proximity sensor, accelerometer, gyroscope, GPS, fingerprint scanner, cameras, speakers, vibration motor, USB port, SIM tray detection.
EFS Backup: The combination firmware provides root ADB access, making it easy to back up the EFS partition (which contains IMEI and network certificates) before performing risky modifications.
Network Unlock Preparation: Some network unlocking tools require the device to be in combination firmware for direct modem access.
Debugging: Developers use combination firmware to debug hardware issues without Samsung's software stack interfering.
Where to Download Combination Files
Combination files are available from Samsung firmware databases. Search for your exact model number + "combination" on SamMobile, SamFW, or specialized GSM forums. Make sure the combination file version matches your device's bootloader version — you cannot flash a combination file with a newer bootloader than what your device currently has.
How to Flash Combination File
- Download and extract the combination file ZIP. Inside you will find a single large .tar.md5 file.
- Install Samsung USB drivers on your PC.
- Boot your Galaxy S26 Ultra into Download Mode (Vol Down + Vol Up + USB cable).
- Open Odin 3.14.4.
- Load the combination .tar.md5 file in the AP slot. Leave BL, CP, CSC empty.
- Check Auto Reboot and F. Reset Time.
- Click Start.
- Wait for PASS. The device reboots into the combination firmware.
The combination firmware boots into a basic Android interface with diagnostic tools and service menus. There is no lock screen, no Google setup, and no FRP.
Using Combination Firmware for FRP Bypass
- Flash the combination file as described above.
- Once booted, go to Settings → Accounts and verify no Google account is present.
- Now flash the full stock firmware via Odin (BL + AP + CP + HOME_CSC).
- Use HOME_CSC (not CSC) to avoid triggering FRP on the stock firmware.
- After the stock firmware boots, set up the device with your own Google account.
Important Warnings
Combination firmware is NOT for daily use. It lacks drivers, optimizations, and Google services. It is purely a diagnostic/service tool.
Always flash stock firmware after using combination. Do not leave the device running on combination firmware — it is not secure and not functional for normal use.
Match bootloader versions. If your device has bootloader U2, you need a combination file for U2 or earlier. Attempting to flash a combination file with bootloader U3 on a device currently at U2 will fail.
Combination firmware does not trip Knox. Flashing a combination file does not trip the Knox counter, since it is Samsung's own factory firmware. However, if your Knox is already tripped from previous rooting, it remains tripped.
Troubleshooting
Odin FAIL when flashing combination: Bootloader version mismatch. Download a combination file matching your current bootloader version.
Device stuck on Samsung logo after combination flash: Wait 5-10 minutes — combination firmware boots slower than stock. If it does not boot after 15 minutes, reflash via Odin.
No ADB access in combination firmware: Some newer combination files require enabling USB debugging manually in Settings → Developer Options.
Guide by XDA Unlocker Team. Last updated: July 2026.