I updated normal system updates this morning because I have not updated for 2 weeks. After restarting the system, the boot was not started showing this error.
[OK] Started GNOME Display Manager.t Dispatcher Service...ed database.s.pp link was shut down....
so, I tried doing boot repair USB and was able to see the boot setting but when I chose previous generic recovery mode, only black scene is shown. My laptop is old model Lenovo with AMD graphic. I used 18.04 since released day and it was fine till now.
is there a way to solve via safe mode console? or just back up data via live CD and have to reinstall?
thanks for suggestions. I found out that latest kernel seems to have a few problems with graphics driver from this repo ppa:oibaf/graphics-drivers. So, I am using fine without it :)