Ubuntu 16.04二次启动异常：选Ubuntu后自动重启，求非重装方案

Hey there, I know it's super stressful when your Ubuntu won't boot properly—especially since you don't want to lose any of your files. Let's walk through step-by-step fixes to get you back into your system without reinstalling anything.

First: Try Recovery Mode (The Most Likely Fix) #

Your system's recovery mode has built-in tools to tackle common boot issues. Here's how to access it:

• When you see the GNU GRUB screen, select Advanced options for Ubuntu (skip the regular Ubuntu entry for now—we know it just restarts!)
• From the list, pick the option labeled Ubuntu, with Linux [your kernel version]-generic recovery mode (it'll be near the top, not the "upstart" or "memtest" options)
• You'll land on a recovery menu with several tools. Let's start with two key fixes:

1. Repair File System Corruption #

File system glitches often cause instant restarts when trying to boot. Here's how to fix them:

• In the recovery menu, select fsck (file system check)
• When prompted "Continue to remount your root file system in read/write mode?", select Yes
• Let the tool run—it'll scan and fix any corrupted files on your drive. This might take a minute or two depending on your disk size.
• Once it's done, select reboot from the recovery menu and check if you can boot into the regular Ubuntu login screen.

2. Reinstall GRUB Boot Loader #

If the file system check didn't work, the GRUB boot loader might be corrupted. Let's repair that:

• Go back to the recovery menu and select root (this gives you full system access via command line)
• First, make your system partition writable (it's read-only by default in recovery mode):

  mount -o remount,rw /
  

• Next, reinstall GRUB to your main drive. For most laptops/desktops, this will be /dev/sda (if you have an NVMe SSD, it might be /dev/nvme0n1—start with /dev/sda if you're unsure):

  grub-install /dev/sda
  

• Update the GRUB configuration to recognize your Ubuntu installation:

  update-grub
  

• Finally, reboot your system:

  reboot
  

If Recovery Mode Fails: Test an Older Kernel #

Sometimes a recent kernel update causes boot issues. Let's try rolling back to an older kernel:

• From the GRUB screen, go to Advanced options for Ubuntu again
• This time, pick one of the older kernel entries (not the recovery mode one—just the regular older version, like Ubuntu, with Linux 5.15.0-78-generic if the latest is 5.15.0-80)
• If this boots you into the login screen successfully, the problem is with the new kernel. Here's how to remove it:
  • Open a terminal (press Ctrl+Alt+T)
  • List all installed kernels to find the problematic one:

    dpkg --list | grep linux-image
    

  • Uninstall the problematic kernel (replace [version] with the actual number, like 5.15.0-80):

    sudo apt purge linux-image-[version]-generic
    

  • Update GRUB to remove the old kernel from the menu:

    sudo update-grub
    

Last Resort: Use an Ubuntu Install USB #

If none of the above works, you can use an Ubuntu installation USB to access your files and fix the boot:

1. Create a bootable Ubuntu USB on another computer (use the same Ubuntu version as your installed system)
2. Boot your problematic computer from the USB, select "Try Ubuntu" (don't install!)
3. Once in the live environment, open a terminal and run these commands:
   • Find your system partition (usually /dev/sda2 or /dev/nvme0n1p2):

     sudo fdisk -l
     

   • Mount your system partition:

     sudo mount /dev/sda2 /mnt
     

   • Reinstall GRUB from the live environment:

     sudo grub-install --root-directory=/mnt /dev/sda
     

   • Update GRUB:

     sudo update-grub --root-directory=/mnt
     

   • Unmount the partition and reboot:

     sudo umount /mnt
     reboot
     

All these steps are designed to preserve your files—none of them will erase your personal data. Take it slow, and if one step doesn't work, move to the next.

内容的提问来源于stack exchange，提问作者Abdessamad Hayani