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.
ACPI BIOS Error(Bug): could not resolve symbol \_SB.PCI0.LPCB.HEC.CHRG, ae_not_found
.....something.....something
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(5.8.0.34 /.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.