I also ran into the exact same problem with Xperia 10 IV. Flashing from new win 11 laptop and old win 10 laptop. No difference. Then flashing AOSP with Emma. Ok. Tried flashing several times but no luck. I also tried running fastboot commands from flash-on-windows.bat from a cmd promt skipping the first one “fastboot reboot fastboot” whitch starts gui mode on phone. Most off them executes successfull except flashing “vendor_boot.img”.
Output from console.
fastboot flash vendor_boot_a vendor_boot.img
Sending ‘vendor_boot_a’ (328 KB) OKAY [ 0.016s]
Writing ‘vendor_boot_a’ FAILED (remote: 'Flashing is not allowed for partition
')
fastboot: error: Command failed
fastboot flash vendor_boot_b vendor_boot.img
Sending ‘vendor_boot_b’ (328 KB) OKAY [ 0.016s]
Writing ‘vendor_boot_b’ FAILED (remote: 'Flashing is not allowed for partition
')
fastboot: error: Command failed
Linux Ubuntu (ubuntu-24.04.1-desktop-amd64.iso ON Oracle VirualBox)
Almost the same error.
Found XQ-CC54, serialn:XXXXX, baseband:65.1.A.5.65, bootloader:6375-0001_X_Boot_SM6375_LA2.0.1_T_106
Found matching device with serial XXXXX
Fastboot command: fastboot -s XXXX
…
…
Blue led lit on phone
After 5-10 min.
Phone displays fastbootd gui.
I select Reboot system now.
Phone boots into android AOSP again.
