While I was upgrading to Ubuntu 15 (the development version), my system crashed. After I restarted the laptop, I saw a kernel panic. I also did a memtestx86 which didn't find any error.
more info :
Before doing upgrade i have changed my default desktop to gnome which by entering wrong commands i lost some packages .to revert the previous desktop i removed all the packages and then installed them then i face that some packages weren't still installed . after i run terminal and started to upgrade ( i found it good to troubleshot the problem by upgrading somehow ) however after crash i got that screen by the way i have faced another screen after this one which backed to the first again
Best Answer
This is not "memory issues or BIOS stuff" at all. The panic screen — which you have not transcribed in full in your question but really should so that the text will be indexed and people will find it in the future — says
Comm: sh. That, plus the knowledge that this is the panic screen that results when process #1 exits with status code 127, tells us that you booted withinit=/bin/sh, or that this is aninitshell script that is provided in an initramfs.In the former case, you explicitly did something to cause the shell to exit. In the latter case, something aborted within the shell script, which would have most likely printed an error message that has unfortunately scrolled off the screen.
You need to find out what that error is. Without it, you cannot diagnose this problem, as it could be any one of a number of very different things. Here are just some of the various possibilities:
Booting with a serial console (that can scroll back or display more than the 24 lines that your laptop's console does) attached is one way to find this out. Persuading the boot loader to switch the screen into, say, 50 line mode would be another.
Further reading