Well, crap. I felt brave and let 18.10 install over 18.04, and it apparently didn't go well.

I'm hitting a kernel panic at boot (error loading libargon2.so.0).

I'm fairly new to Ubuntu - is there a way to recover this - perhaps from a usb boot installation, without losing all of my current settings and applications?

  • you can use this link, may be it helps, you don't tell us what is really wrong so... askubuntu.com/questions/162075/… – ft18 Oct 19 '18 at 3:53
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    Not sure what else I can tell you. Boot fails due to a kernel panic caused by the missing file. But there are some good links there. I'll see if I can fix it from a live usb. – Alan Oct 19 '18 at 4:03

I just solve it. I tried different solutions so maybe some steps are redundant or missing:

  1. Boot from Ubuntu Live USB (in my case it was 18.04 LTS).
  2. Open Nautilus.
  3. In left bottom side click on "Other locations"
  4. Select your old Ubuntu drive and open it (you will be in the root folder of your old Ubuntu, in my case it was something like /mnt/f3kljjhfu23oghggnmnjyy)
  5. Open terminal in this folder.
  6. Make mirrors for folders:

    sudo mount --bind /dev ./dev
    sudo mount --bind /sys ./sys
    sudo mount --bind /proc ./proc
  7. After this command you will be like root for old Ubuntu:

    sudo chroot .
  8. Open a browser and download deb file of libargon2-0 for your OS from Debian packages repository (in my case file was named like libargon2-0_0~20171227-0.1_amd64.deb).
  9. Copy the downloaded file to tmp file of your old Ubuntu (/mnt/f3kljjhfu23oghggnmnjyy/tmp)
  10. Install the downloaded deb file using the terminal from step #7 (so it will be installed to old Ubuntu):

    dpkg --install /tmp/libargon2-0_0~20171227-0.1_amd64.deb
  11. After successful package installation restart your computer and boot to your old Ubuntu (you may want to press Esc on Ubuntu's loading screen to watch the status of loading)

PS. You may like an instruction from this guy, which helped me a lot - Install package to Ubuntu 16.04 installation while booted into live cd


Alternatively, if you used BTRFS for your drives, you could restore to a snapshot from before the installation. It would work best.

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