I have a problem where if I turn on the computer I tried to boot to Kubuntu, it just takes me to a black screen. It sticks there with no output and no hint of what's going on except that the Caps Lock indicator light on my keyboard flashes on and off (weird, right?)
If I then turn off the computer (by holding down the power button for a few seconds), and turn it back on, I get a boot menu where I can choose 'Advanced options for Ubuntu', and that lists different versions, recovery modes, some of which work just fine.
That's what I've bee doing for the two weeks or so I've had this problem, and it worked until just now. The alternative options only booted me into the command line. I was able to fix this with this solution, so now I'm typing this from my desktop.
I'm reluctant to turn off the computer in case it happens again, and I'd like to just tear out the root of the problem.
Kubuntu boots to a black screen with the following error messages.
[ 0.528611] EDD information not available.
[ 0.530345] PM: Hibernation image not present or could not be loaded.
[ 0.532079] md: Waiting for all devices to be available before autodetect
[ 0.533721] md: If you don't use raid, use raid=noautodetect
[ 0.535830] md: Autodetecting RAID arrays.
[ 0.537468] md: Scanned 0 and added 0 devices.
[ 0.539110] md: autorun ...
[ 0.540769] md: ... autorun DONE.
[ 0.542435] VFS: Cannot open root device "mapper/kubuntu--vg-root" or unknown-block(0,0): error -6
[ 0.544121] Please append a correct "root=" boot option; here are the available partitions:
[ 0.545812] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[ 0.547512] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-65-generic #86-Ubuntu
[ 0.549222] Hardware name: LENOVO 80G0/Lancer 5A6, BIOS A7CN40WW 07/18/2014
[ 0.550945] 0000000000000086 000000009b7de47d ffff88017a403de8 ffffffff813f8743
[ 0.552706] ffffffff81ca4618 ffff88017a403e80 ffff88017a403e70 ffffffff8118d367
[ 0.554481] ffff880100000010 ffff88017a403e80 ffff88017a403e18 000000009b7de47d
[ 0.556229] Call Trace:
[ 0.557931] [<ffffffff813f8743>] dump_stack+0x63/0x90
[ 0.559674] [<ffffffff8118d367>] panic+0xd3/0x215
[ 0.561400] [<ffffffff81f5e576>] mount_block_root+0x201/0x294
[ 0.563126] [<ffffffff81f5e66e>] mount_root+0x65/0x68
[ 0.564842] [<ffffffff81f5e7ab>] prepare_namespace+0x13a/0x172
[ 0.566557] [<ffffffff81f5e21b>] kernel_init_freeable+0x1e9/0x212
[ 0.568263] [<ffffffff8182ff40>] ? rest_init+0x80/0x80
[ 0.569959] [<ffffffff8182ff4e>] kernel_init+0xe/0xe0
[ 0.571625] [<ffffffff8183ca0f>] ret_from_fork+0x3f/0x70
[ 0.573263] [<ffffffff8182ff40>] ? rest_init+0x80/0x80
[ 0.574951] Kernel Offset: disabled
[ 0.576541] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)