I was using Ubuntu 14.04 Server then upgraded to Ubuntu 16.04 and then to the latest LTS version of Ubuntu 18.04 Server.
Updates changed the running kernel version too. Now my computer has two Linux kernels, 4.15.0-43 generic and 4.4.0-141-generic. The first option is 4.15.x and it's stuck at a kernel panic if it is selected.
Here are screenshots of the error:
And here is my installed kernels:
Kernel 4.4.0-141 boots successfully. but I'd like to use new version of Linux kernel.
Also there is another issue with Ubuntu 18.10. There was the same error, but after community updated Linux kernel version to 4.18.x the problems were gone.