[SOLVED] Can't boot Tara after kernel update: can't restore via Timeshift

[SMG]

Partition 3 does not allow me to run a check.

Probably because it is mounted and in use. See my previous post about your swap parition.

[PerpetualNewbie]

Ok, so I am not able to find any screen that allows me to remove a kernel. Am I in the wrong menu?

Menu options are:
UEFI - Ubuntu
UEFI N/W IPV6 Network - intel ethernet Connection (3) 1219-LM
UEFI N/W IPV4 Network - intel ethernet Connection (3) 1219-LM
Boot from file

When I tried UEFI - Ubuntu, I got a choice of
Ubuntu
Advanced options for Ubuntu
System Setup

If I choose Ubuntu, I get a failed boot with the dreaded "Couldn't get size" message with a prompt for the cursor that says: (initramfs) [flashing cursor]
If I choose System Setup, I get bounced back to the startup menu that shows boot options
If I choose Advanced Options for Unbuntu, I get a list of versions of what I think was linux distros, not kernels.

Choices look like this:
Ubuntu, with Linux 4.15.0-147-generic (recovery mode)
Ubuntu, with Linux 4.15.0-147-generic
Ubuntu, with Linux 4.15.0-144-generic (recovery mode)
Ubuntu, with Linux 4.15.0-144-generic
Ubuntu, with Linux 4.15.0-143-generic (recovery mode)
Ubuntu, with Linux 4.15.0-143-generic
Ubuntu, with Linux 4.15.0-142-generic (recovery mode)
Ubuntu, with Linux 4.15.0-142-generic

Anyhow, when I choose one, I get the dreaded "Couldn't get size" message with a prompt for the cursor that says: (initramfs) [flashing cursor]

[SMG]

Ok, so I am not able to find any screen that allows me to remove a kernel. Am I in the wrong menu?

You do not need to remove a kernel in order to boot into an older kernel. You boot into the older kernel and then delete the newer one in Update Manager after the operating system boots (using the older kernel). You can only remove kernels which are installed but are not active.

To boot into an older working kernel you use the options I highlighted in your post.

Menu options are:
UEFI - Ubuntu
UEFI N/W IPV6 Network - intel ethernet Connection (3) 1219-LM
UEFI N/W IPV4 Network - intel ethernet Connection (3) 1219-LM
Boot from file

When I tried UEFI - Ubuntu, I got a choice of
Ubuntu
Advanced options for Ubuntu
System Setup

Choices look like this:
Ubuntu, with Linux 4.15.0-147-generic (recovery mode)
Ubuntu, with Linux 4.15.0-147-generic
Ubuntu, with Linux 4.15.0-144-generic (recovery mode)
Ubuntu, with Linux 4.15.0-144-generic
Ubuntu, with Linux 4.15.0-143-generic (recovery mode)
Ubuntu, with Linux 4.15.0-143-generic
Ubuntu, with Linux 4.15.0-142-generic (recovery mode)
Ubuntu, with Linux 4.15.0-142-generic

Anyhow, when I choose one, I get the dreaded "Couldn't get size" message with a prompt for the cursor that says: (initramfs) [flashing cursor]

You could choose the last option I highlighted or any of the ones below it. You would not want to choose either of the ones with the latest kernel (4.15.0-147).

If that is what you did, there are actually several different types of "Couldn't get size" messages possible, so if you could take a photo of what you are seeing (or type it exactly) that would be helpful.

I did find this How Do I Start Ubuntu From Initramfs?, but I'm not sure if that is what you are seeing, so it might not be appropriate for your situation.

[Jo-con-Ël]

Partition1 on the left looks ok, no damage detected.

Partition 3 does not allow me to run a check...

The only one partition I told to check was the root (sda2, partition 2) and you don't mention anything about checking that partition...

Also I told to unplug Linux Mint USB when trying to boot Linux Mint (Ubuntu) Installed after checking to avoid message about sdb not sbd.

Any way those messages you can see in screen are previous to initramfs (i.e. before checking and mounting system partition/s) and most probably has nothing to be with the real problem, even they are not problems by their self. Couldn't get size: 0x00000000000000e looks like to be related with firmware/EFI settings and maybe it is harmless (in my case it happens, depending on the kernel I use, when trying to get UEFI MokListRT but Secure Boot is disabled so nothing to do there) and sda/sdb lines are normal when examining devices (internal or external as USB).

As per last link SMG provide, busybox results in that <initramfs> shell most the times (not in all cases) when need to check root or another partition by hand 'cause "normal" checking system does went wrong. Write exit to see and then you can try checking/repairing from that shell as indicated (with fsck -y /dev/sda2) if manual checking is needed .

If it fails, depending on warnings you receive, you will need to check from a Linux Live session as indicated in my post (look at here by example).

Once you are sure root filesystem is clean if initramfs results after reboot (with the last and previous kernels) you will need to dischard other things as you didn't change any setting in UEFI/BIOS: SATA mode (AHCI not IDE or RAID), Secure Boot (disable if no TPM is present or it is off),...

PD:You'd better take a photo to share than trying to write about what you see in screen.

[PerpetualNewbie]

Hi SMG and Jo-con-Ël

Things look normal at boot up!

Thanks for the comments, the fsck -y /dev/sda2 did the trick, I ran it once and it fixed a bunch of stuff, then I ran it again and it didn't need to fix anything.

I am so grateful for the help and advice. Thank you a million, squillion!

This has been marked RESOLVED.

[karlchen]

Note:
swap devices do not have a filesystem, which could be checked by fsck. swap devices are raw devices, where the OS mirrors parts of the main memory.
This is why partition #3 cannot be checked by fsck. fsck cannot check it, even in case the swap device is not in use at all (swapping disabled).