Comment 2 for bug 1868015

during upgrade from 16.04 to 18.04, system popup a dialog, say the grub config file has been modified. Ask whether to keep the modified configure or replace with a new one. I choose the last option: rerun a shell script to detect the situation again. Then an hour passed and the dialog lock into a seemly deadlock status. Ctrl+Alt+F2, switch to the console, ps -aux|grep 'grub-pc', kill the two processes...