Proxmox upgrade causes Kernel panic

[nitaish]

We were trying to upgrade Proxmox to the latest version 4.4 from the version 4.2. During the upgrade, suddenly two nodes went down and now they don't boot. We encounter the following error

Kernel panic - not syncing: VFS: unable to mount root fs on unknown-block(0,0)

What could be the problem and how to resolve?

 

[morph027]

Which root filesystem? Can you press "e" in grub and show the config (screenshot)?

 

[nitaish]

It does not even show grub and directly shows the kernel panic error.

 

[nitaish]

Here is the screenshot

 

[morph027]

Can you try to hold shift while starting up? there must be a grub, which might not show, if there's only one kernel.

 

[troycarpenter]

I had this issue on one of my nodes after the upgrade to 4.4. I tried using system restore CD, but no matter how many times I reinstalled grub, I got the same issue. I ended up reinstalling the node and using the online documentation to bring it back online in the cluster.

 

[LnxBil]

Check grub config and also check initramfs. Often you can boot the old kernel manually with grub and you always use grub (bootloader) to load linux. Linux does not boot itself up from nothing.

 

[zdenbe]

Hello, same problem (2 from 4 nodes).
Previous config not working - controller not found / vg not found

edit: grub option with old kernel (3.16) and "dpkg --configure -a" helped me.

Setting up pve-kernel-4.4.35-1-pve (4.4.35-76) ...
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 4.4.35-1-pve /boot/vmlinuz-4.4.35-1-pve
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 4.4.35-1-pve /boot/vmlinuz-4.4.35-1-pve
update-initramfs: Generating /boot/initrd.img-4.4.35-1-pve
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 4.4.35-1-pve /boot/vmlinuz-4.4.35-1-pve
Generating grub configuration file ...
packet_write_wait: Connection to IP port 22: Broken pipe

 

[LnxBil]

Have you changed your SSH or hostname configuration?

 

[TChrizzle]

I can confirm running "dpkg --configure -a" fixed the issue. It seems like when initially running the configure via apt-get dist-upgrade the grub boot script doesn't generate nor include the initrd in the grub.cfg; causing the system to crash. This is upgrading from
Proxmox Virtual Environment 4.2-2/725d76f0 to Virtual Environment 4.4-12/e71b7a74.