I have some troubles with Ubuntu 18.04 (it installed with windows, but I not using it) and decided to install another linux distro (Manjaro, installation EFI). Installation was success, but manjaro didn't install own grub (early I installed two linux system, and it using grub of last installed os). But after restart, grub was from ubuntu and manjaro wasn't there. I choose to boot ubuntu. And it statrting boot to long: about 30 seconds black screen. Then about 2 min when was ubuntu logo. Then I log in, and in terminal run command
sudo update-grub. It found new system and defined it as manjaro. After reboot, in grub I choose manjaro, but there was only errors, I shut it down, and boot into ubuntu (again long boot). Via Gparted I delete all disks of manjaro and again run
sudo update-grub. I was thinking that solve problem with long boot of ubuntu. But no! Manjaro is gone, and ubuntu boot two minutes on SSD! What is wrong with that???
Hope, someone know how to repair that. I edit this file
/etc/default/grub by changing
GRUB_CMDLINE_LINUX_DEFAULT and get some output when it booting (see on image)