Hey there, let's figure out why your Ubuntu 16.04 system crashed after restoring your tar backup, and walk through how to fix it. The root cause almost always comes from how the backup was created or how the restore was performed—let's break it down step by step.

Why Your System Crashed #

Your backup and restore steps missed critical exclusions and overwrote system-specific files that don't play well with a fresh installation:

• Incomplete backup exclusions: The original backup command didn't exclude virtual/temporary filesystems like /proc, /sys, /dev, /tmp, and /run. These directories contain dynamic system data generated at boot, not persistent files. Restoring them conflicts with the fresh system's own dynamic files, breaking boot processes.
• Overwriting system-critical files: Restoring the entire backup directly to / overwrote the fresh install's bootloader (grub), kernel, and partition configuration (/etc/fstab). Since you wiped the drive for dual-boot, the partition layout changed—your old fstab references UUIDs that no longer exist, causing mount failures on boot.

Step-by-Step Fixes #

1. Boot into Ubuntu Live Mode #

Grab your Ubuntu 16.04 installation USB/CD, boot from it, and select "Try Ubuntu without installing". This lets you access your installed system without booting it directly.

2. Mount Your System Partition #

First, identify your system partition (usually /dev/sda1 or similar) using lsblk, then mount it:

sudo mkdir /mnt/ubuntu
sudo mount /dev/sda1 /mnt/ubuntu

3. Repair the System Configuration #

a. Fix the fstab File

The old fstab from your backup is pointing to invalid partitions. Replace it with the fresh install's fstab (you can find a backup in /mnt/ubuntu/etc/fstab~ if it exists, or generate a new one):

# Backup the broken fstab first
sudo cp /mnt/ubuntu/etc/fstab /mnt/ubuntu/etc/fstab.broken
# Copy the fresh install's backup fstab (if available)
sudo cp /mnt/ubuntu/etc/fstab~ /mnt/ubuntu/etc/fstab
# If no backup exists, generate a new one using blkid to get current UUIDs
blkid # Note the UUID of your system partition
sudo nano /mnt/ubuntu/etc/fstab
# Replace the old UUID line with something like:
# UUID=your-new-uuid / ext4 errors=remount-ro 0 1

b. Reinitiate System Boot Components

Chroot into your mounted system to update the initramfs and grub, which fixes kernel/bootloader mismatches:

sudo mount --bind /dev /mnt/ubuntu/dev
sudo mount --bind /proc /mnt/ubuntu/proc
sudo mount --bind /sys /mnt/ubuntu/sys
sudo chroot /mnt/ubuntu
# Update initramfs to fix kernel module issues
update-initramfs -u
# Update grub to recognize the current partition layout
update-grub
exit

4. Correct Your Backup Process for Future Use #

To avoid this issue next time, use a proper backup command that excludes non-persistent directories:

cd /
sudo tar -cvpzf backup.tar.gz \
  --exclude=/backup.tar.gz \
  --exclude=/proc \
  --exclude=/sys \
  --exclude=/dev \
  --exclude=/tmp \
  --exclude=/run \
  --exclude=/mnt \
  --exclude=/media \
  --exclude=/lost+found \
  /

When restoring, avoid overwriting /boot, /etc/fstab, and /etc/default/grub unless you're sure the partition layout is identical to the original system.

Verify the Fix #

Unmount the partitions and reboot:

sudo umount /mnt/ubuntu/dev
sudo umount /mnt/ubuntu/proc
sudo umount /mnt/ubuntu/sys
sudo umount /mnt/ubuntu
sudo reboot

If it still crashes, check the boot logs in /var/log/boot.log or /var/log/syslog from Live Mode to pinpoint specific errors (e.g., driver conflicts, filesystem corruption).

内容的提问来源于stack exchange，提问作者Mohit