Thanks for the information I glad I’m not the only one
I also was runniing jetson nx without sd card with nvme and was told is was impossible but it seemed to work before 5.1.2!!!
To solve the problem if I did the following everthing would work ok
I put SD card in xavier nx
put xavier NX in reset mode
the following directory is on my pc.
“~/nvidia/nvidia_sdk/Jetpack_5.1.2_Linux_JETSON_NX_TARGETS/Linux_for_tegra/”
having got to the directory I run the following command
sudo ADDITIONAL_DTB_OVERLAY=“BootOrderNvme.dtbo” ./tools/kernel_flash/l4t_initrd_flash.sh --external-device nvme0n1p1 -c ./tools/kernel_flash/flash_l4t_external.xml --showlogs --network usb0 jetson-xavier-nx-devkit nvme0n1p1
and if by magic the xavier nx flashed ok (only the os)
I then went back to sdkmanager and updated all the other iterms exept for the flash.
Lets hope next time editing the following file
etc/apt/sources.list.d/nvidia-l4t-apt-source.list
and upgrading will work.
cheers