I'm running an Ubuntu 16.04 (ext4) and Windows 10 (ntfs) dual boot environment which worked perfectly until I seemed to have crashed it by switching temporarily from UEFI Only to Legacy Only in my bios to run hard drive diagnostic tools from USB.
Now the initial splash screen has changed and the grub menu (version 2.02~beta2-36ubuntu3.7) shows up in much lower resolution (640x480) then before.
This is not really a problem for me, but when I choose to start Ubuntu this message pops up for a second:
error: Invalid video mode specification 'text'. Booting in blind mode
Then two more message lines are shown:
[1.895670][drm: intel_set_pch_fifo_underrun_reporting [i915]] *ERROR* uncleared pch fifo underrun on pch transcoder A [1.895696][drm: intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun
After this, the Ubuntu loading screen appears in high resolution, but exits in emergency mode where I can login as root user.
When I type in
glxinfo in Terminal I get
Error: unable to open display.
It all seems to me that there is an issue with loading the Intel grahpics driver in Ubuntu (Windows starts without problems).
Has anybody experienced a similar issue before or better can help me to get my Ubuntu booting again? I've searched through the forums, but couldn't find a helpful solution yet. Would be great!
@rod-smith (see answer below) helped me already with UEFI/CMS/Legacy settings and got me back to the previous splash screen and the grub menu in high resolution. However, the main problem:
error: Invalid video mode specification 'text'. Booting in blind mode still persists and I end up in emergency mode. Any more suggestions how to handle this?
If it helps, I'm running a Lenovo Thinkpad X1 Carbon from 2013.
When I run
journalctl -xb in emgergency mode, some red messages show up. Within them the messages
fsck failed with error code 4 and
Failed to Start File System Check on /dev/disk/by-uuid/..... Maybe this can help.
Update 3 The problem is solved. See my answer below.