You can install SigintOS 1.1 on your hard disk by following the steps below.

Step 1
Uninstall ubiquity software
sudo apt-get remove ubiquity

Step 2
Rebuilding the ubiquity software
sudo apt-get install ubiquity ubiquity-frontend-gtk

Step 3
Copying boot files to / target directory when files are copied after ubiquity is run and all settings are made

sudo ubiquity

After opening ubiquity, enter the following commands when the files begin to be copied after the language, country, partitioning and user creation screen.

sudo mkdir /target/boot

sudo cp /cdrom/casper/initrd.gz /target/boot/initrd.gz
sudo cp /cdrom/casper/vmlinuz /boot/vmlinuz

sudo cp /cdrom/casper/vmlinuz /target/boot/vmlinuz
sudo cp /cdrom/casper/vmlinuz /boot/vmlinuz-4.15.0-43-generic

sudo cp /cdrom/casper/vmlinuz /target/boot/vmlinuz-4.15.0-43-generic

After entering these commands, wait for the ubiquity setup to finish. When the screen shows that the installation is completed successfully, the system will be installed successfully.