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

[Xun468]

I was using my ubuntu guest just fine yesterday, but today when I start it up I am getting a kernel panic - not syncing: VFS : unable to mount root fs on unknown-block (0,0) error. This is after I encounter a GNU-Grub screen where I select an option to boot, I have not seen this screen before today.

The host is 64-bit windows 10
The guest is 64-bit Ubuntu 18.x (installed as 4, may have been updated)
I have tried cold restarting the guest on virtual box, reducing the amount of RAM available, running virtual box as administrator, and restarting the host computer.

Does anyone have some advice on how I can fix this?


Edit: uploaded correct log

[mpack]

To me that seems like the host VDI file is corrupted, perhaps the host drive is corrupted. The easiest fix is to run chkdsk on the host drive, then restore the VDI from the last backup.

I don't know how "reducing the RAM available" is expected to help! Depending on what you reduced it to, that could just introduce more problems. In fact none of the measures you mention would be expected to be effective.

[Xun468]

Thanks! I was not sure if it was supposed to help, but it seemed that those steps were recommended for similar errors online. I am not sure what lines to look for in the logs specifically so I tried a bunch of stuff first lol. Does the VDI automatically backup?

[mpack]

Backups are made by copying files to secondary storage, so no - that does not happen automatically, at least not on Windows PCs.

Btw, this is not a discussion about the guest. Moving this topic to "Windows Hosts".

[Davey]

For what it's worth:

First time boot, crashes with error message as original poster gives.

Second boot, gives grub. Can specify original kernel that came with 18.04

Boots fine.

Therefore, inclined to say, issue with Ubuntu Guest and not Windows Host. No file corruption exists. Kernel (its compatibility with VirtualBox) at fault.

Do with this as you will.