Ubuntu 20.04启动故障及Live U盘"incompatible license"报错问题求助

Hey there, let's break down your issue and walk through the fixes step by step—this sounds like a combination of a damaged partition table and a Secure Boot-related problem with your live USB.

先搞清楚为什么会出现这些问题 #

• Invalid Partition Table & Grub Rescue: When your laptop crashed mid-SSD format, it likely corrupted the partition table (either MBR or GPT) on your system drive. Grub relies on this table to find your Ubuntu installation, so a broken table leaves it stuck in rescue mode.
• "Incompatible license" on live USB: This almost always ties to Secure Boot in your BIOS/UEFI. Secure Boot checks that bootable media has valid, signed firmware—if your live USB was improperly created (corrupted mirror, wrong tool settings) or Secure Boot is enforcing strict checks, it throws this error because it can't verify the USB's signature.

Step 1: Fix the live USB "incompatible license" error #

First, we need to get into a live Ubuntu environment to repair your system. Here's how:

1. Reboot your laptop and enter BIOS/UEFI settings (usually press F2, F10, or Del when the manufacturer logo appears).
2. Look for the Secure Boot option and set it to Disabled (we can re-enable it later once the system is fixed).
3. Save your BIOS settings and reboot, then try booting from the live USB again—it should load normally now.
4. If it still fails:
   • Download a fresh copy of the Ubuntu 20.04 ISO, and verify its checksum to ensure it's not corrupted.
   • Use the official Rufus tool to re-make the live USB: select the ISO, choose the correct partition scheme (GPT for UEFI, MBR for Legacy BIOS), and let it do its thing.

Step 2: Repair the damaged partition table #

Once you're in the live Ubuntu environment:

1. Open a terminal and run sudo parted -l to identify your system drive (it'll be something like /dev/sda for a SATA drive, or /dev/nvme0n1 for an NVMe SSD).
2. Fix the partition table based on its type:
   • For MBR partition tables:
     1. Install TestDisk: sudo apt update && sudo apt install testdisk
     2. Run it: sudo testdisk
     3. Select your system drive, choose Intel/MBR, then Analyze > Quick Search.
     4. TestDisk will find your lost partitions—select the ones that belong to your Ubuntu installation, then choose Write to save the repaired partition table.
   • For GPT partition tables:
     1. Run GDisk: sudo gdisk /dev/sdX (replace sdX with your system drive letter, e.g., /dev/sda)
     2. Press r to enter repair mode, then c to check the GPT table for errors.
     3. Follow the prompts to fix any detected issues, then press w to save the changes.

Step 3: Repair Grub bootloader #

With the partition table fixed, let's get Grub working again:

1. Mount your Ubuntu root partition (find it with sudo parted -l—it's the large EXT4 partition):

   sudo mount /dev/sda2 /mnt  # Replace sda2 with your root partition
   

2. If you have an EFI partition (small FAT32 partition, typical for UEFI systems), mount it too:

   sudo mount /dev/sda1 /mnt/boot/efi  # Replace sda1 with your EFI partition
   

3. Mount critical system directories to chroot into your installation:

   for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
   

4. Switch to your system's root environment:

   sudo chroot /mnt
   

5. Reinstall Grub:
   • For UEFI systems: sudo grub-install /dev/sdX (use the drive letter, not a partition, e.g., /dev/sda)
   • For Legacy BIOS systems: sudo grub-install /dev/sdX
6. Update Grub to detect your system:

   sudo update-grub
   

7. Exit chroot and reboot:

   exit
   sudo reboot
   

Alternative: Use Boot Repair (simpler option) #

If the above steps feel too manual, you can use Boot Repair once the partition table is fixed:

1. In the live environment, install Boot Repair:

   sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt update && sudo apt install boot-repair
   

2. Run it with sudo boot-repair, select the Recommended repair option, and let it automate the Grub and partition fixes.

备注：内容来源于stack exchange，提问作者mans