I have a Dell XPS 15 9550 and a encrypted Ubuntu which will not boot. At the beginning iI updated/upgraded the current OS which resulted in the following output after reboot.

enter image description here

ACPI BIOS Error(Bug): could not resolve symbol \_SB.PCI0.LPCB.HEC.CHRG, ae_not_found

    Kernel Panic - not syncing VFS Unable to mount root fs on xxxx/block

I thought that is not good. Then I decided to update the BIOS from 1.12.xx to 1.14.xx which could fix the issue. After successfully update bios, i restart my notebook with the following kernel( /.55/.53/.59), which led to the following output:

Loading Linux 5.8.0.X-generic...
Loading initial ramdisk...  

In addition to that I found people with a similar issues (with the following solution), but I didn't find the PPT settings.

I had the same problem. My computer is a Dell Inspiron 15.

The problem is with UEFI. To fix it you can turn off PPT in the UEFI/BIOS options and enable Legacy Boot.

I thought maybe I'd chroot my Ubuntu with a live USB and install another kernel, but I thought I'd ask the community before the attempt because I tried that with the kernels that I mentioned above.

  • Many Dells have needed UEFI update. That may reset UEFI settings and you have to redo some, check all the settings you originally made to UEFI. But UEFI update would have just added issues. Are you dual booting? Do you have good backups? Anyone with encryption must have good backups. Lets see details, use ppa version with your live installer (2nd option) or any working install, not Boot-Repair ISO: Please copy & paste the pastebin link to the Boot-info summary report ( do not post report), do not run the auto fix till reviewed. help.ubuntu.com/community/Boot-Repair
    – oldfred
    Jul 3, 2021 at 18:07
  • Hi @oldfred, thanks for the quick response. No dual booting. I dont have a backup (dont judge me) but the good part is the ssd is not damaged and i mount the partition on ubuntu live usb. Pastebin link Jul 3, 2021 at 21:27
  • Did not show files in ESP which it normally does. And it mounted LVM, but since encrypted did not show some of the files in Ubuntu. Best to mount LVM and decrypt before running Boot-Repair. I might run dosfsck just to see if issue with ESP. Details: askubuntu.com/questions/862724/grub2-failed-to-install/…
    – oldfred
    Jul 3, 2021 at 21:53
  • I've encountered a similar issue on Dell XPS 15 9550. I did reduced the initram size and things got better. ref askubuntu.com/questions/1343808/ubuntu-21-04-not-booting/…
    – morhook
    Jul 28, 2021 at 13:43

1 Answer 1


easy fix, erase DKMS modules

I've experienced this problem now that I upgraded to Ubuntu 22.04 again.

Check the file sizes on /boot of initrd images. Example:

$ ll /boot/initrd.img-5*
-rw-r--r-- 1 root root 93573024 jun  3 01:08 /boot/initrd.img-5.11.0-16-generic
-rw-r--r-- 1 root root 93572036 jun  3 01:08 /boot/initrd.img-5.11.0-17-generic
-rw-r--r-- 1 root root 93560099 jun  3 01:08 /boot/initrd.img-5.11.0-18-generic
-rw-r--r-- 1 root root 20036664 jun  3 18:01 /boot/initrd.img-5.15.0-33
-rw-r--r-- 1 root root 68940452 jun  4 11:49 /boot/initrd.img-5.15.0-35-generic

There all images will go ok. But if you initrd is bigger than 123560099 you'll be experiencing the problem you are seeing. (there's a problem with how memory secuencing/contiguous is handled in the UEFI).

Just erased all DKMS modules on my laptop (like nvidia drivers!) and now I'm able to boot again.

ultra compression part

Another thing that might help is to compress better the initrd with this params on /etc/initramfs-tools/initramfs.conf. Change MODULES to "dep" (instead of most) and COMPRESS with "lz4" instead of zstd:

# ..
# many lines after
# ...

Also install with sudo apt install lz4 before running something like:

sudo update-initramfs -k 5.15.0-35-generic -u

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