Just adding my case here in case it helps someone else with the same error.

I’m running FOG 1.5.10 on RHEL 9.5. In my case the problem was not iPXE, kernels or init.xz, but a broken NFS setup on the FOG server.

When I tried to rerun installfog.sh, it always failed at “Starting NFS server” with a systemd dependency error. Checking systemctl list-dependencies --failed nfs-server.service showed that one dependency was a failed mount coming from /etc/fstab. It was an old ISO mount pointing to a path that no longer existed.

Because that mount failed, nfs-server could not start, and FOS Linux failed to mount its root filesystem over NFS, causing the kernel panic on UEFI clients.

After removing the invalid mount from /etc/fstab, running systemctl daemon-reload, fixing NFS exports and starting nfs-server, I was able to complete installfog.sh and UEFI PXE boot started working again.

@george1421 Thank you so much! I enabled portfast on the switch port, and it works on physical PCs.

Kernel panic - not syncing: VFS: Unable to mount root fs on "/dev/ram0" or unknown-block(1,0) Kernel Offset: disabled ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on "/dev/ram0" or unknown-block(1,0)

But sometimes this error appears even if I haven’t changed anything in the configuration and files. Even if I update or roll back the init.xz or bzImage file to a previous version, it doesn’t help. The only thing that seems to work is setting up a completely new FOG server, but after some time, the problem can come back. How I can find right version or how I can solve this problem? Most time it error on PCs with UEFI