So like many of you, I have been plagued by this error ever since the 224/225 Bios was released.
Strangely, I did not have this problem when I upgraded from 214 to 220 follow by 223 on the same hardware.
I tried to compare what had changed and a little debugging using process monitor, I finally found the answer.
I did a fresh 8.1 install and wipe the original partition clean, that is when I encounter the Bios error.
Using process monitor while filtering winflash.exe, there was an error message saying it cannot access \Device\Harddiskvol2\EFI\Asus\Firmware\T100Ta.bin.
I assigned a drive letter to the EFI partition, access it using administrator and created EFI-ASUS-Firmware folder structure. Viola, the winflash ran like a charm.
Instructions
WARNING: Perform this at your own risks, modifying the EFI partition can render your system unbootable
- Launch cmd with admin permission
- type the following command
- Diskpart
- select disk 0
- List part
- Note the 100MB partition - mine is part 2
- select part 2
- Assign
- Exit
- taskkill /im explorer.exe /f
- Explorer
Explorer should launch and you can access the 100MB EFI partition and create the folder structure
driveletter:\EFI\ASUS\Firmware
Launch Winflash and flash away.
Cheers