Panic on boot - Bricked Kernel during upgrades

(B. Martinez) #1

I have a fpbx distro system, that was updating (system updates, not module updates) and somehow it failed the upgrade. Disk space isn’t an issue. During reboot the system issues a panic and hangs.

The panic error is: “Kernel panic - not syncing: VFS: Unable to mount root fs on unknown -block(0,0)”

If I manually intervene and have Grub boot off previous Kernel, it will boot into Emergency Mode. If I login, then exit, it will finish booting in the old kernel and everything will operate normally up until another reboot (in which case it will panic again). After getting it up, I yum update everything and that did not change/fix the issue.

This is a production system and it’s virtualized. I have current backups, but would prefer to repair the borked update. What is recommended way to get past this properly? It appears I may just need to somehow rebuild that failed kernel install or repair. I have seen some posts talking about rebuilding the ramfs image that the kernel uses during booting. I found a link which references this situation pretty clearly however not sure if others have ran into this before I go cowboy here:

How to Fix Kernel Panic - Not Syncing: VFS: Unable to Mount Root FS on Unknown-Block(0,0)

System Info:

Sangoma Linux 7.8.2003

Kernel that won’t boot: 3.10.0-1127.19.1.e17.x86_64
Kernel that does work (previous version): 3.10.0-957.21.3.e17.x86_64

(Lorne Gaetz) #2

Often you can recover by booting from the working kernel and running

yum reinstall kernel

And then try booting from the new kernel again


You say you are “virtualized” , by what method ?

I ask that because maybe you won’t be able to replace your kernel.

(B. Martinez) #4

It was virtualized from the get go in QEMU as are all the systems we manage. “yum reinstall kernel” solved the problem. We’re back in action without grub manual intervention. Cheers


If you are not yet using gcow2 for your disks, then I encourage you to migrate them thusly and utilize snapshots on a timely fashion.

(system) closed #6

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