NX(emmc-version) flash system to extern SD failed

Hi
we have a custom board which has sd card slot,we want to flash system into sdcard instead NX’s emmc.
we use command “sudo ./flash.sh jetson-xavier-nx-devkit mmcblk1p1”, This command failed.
here are error logs:
[ 133.1108 ] Writing partition secondary_gpt with gpt_secondary_3_0.bin
[ 133.1122 ] […] 100%

[ 133.3311 ] Erasing sdcard: 0 … 0000000074740311: E> NV3P_SERVER: Failed to open instance 0 of device 6.
[ 133.3334 ]
[ 133.3334 ] [Failed]
[ 133.3334 ]
Error: Return value 17
Command tegradevflash_v2 --pt flash.xml.bin --create
Failed flashing t186ref.

hello infovlpwm,

please check external wiki page for the steps to flash device with rootfs on external devices, https://elinux.org/Jetson/L4T/Boot_From_External_Device
you may also refer to similar discussion thread to flash on sdcard, Topic 79833.
thanks

Hi Jerry Chang
There is no l4t-rootfs-uuid.txt file under bootloader/. IN NX L4T 32.4.2version。
How can i do this step :3. Copy PARTUUID to bootloader/l4t-rootfs-uuid.txt

hello infovlpwm,

here’s another approach, you may use Etcher tool to copy an image to an SD card.
please also refer to documentation, Flashing to an SD Card for the steps.
thanks