双引导系统下升级Win8.1至Win10后无法启动Win10及恢复双引导方案咨询

Hey Norris, let's break down your questions step by step—you've got solid backups in place, which is a huge win already!

第一个问题：升级Windows 10后能否重建GRUB，保留现有Linux系统和/home分区？ #

Absolutely, you can rebuild GRUB after successfully upgrading Windows 10 without having to reinstall Linux entirely. Here's how to do it safely:

• Grab your Linux Mint 21.2 Mate installation USB/CD and boot from it.
• Once you're in the live environment, open a terminal and first identify your Linux root partition (you can use lsblk or fdisk -l to find it—look for the ext4 partition that's your / mount point).
• Mount your root partition to /mnt:

  sudo mount /dev/sdXn /mnt
  

  (Replace /dev/sdXn with your actual root partition, like /dev/sda2.)
• If you have a separate /boot partition, mount that too:

  sudo mount /dev/sdYm /mnt/boot
  

• Now chroot into your installed system to gain full access:

  sudo chroot /mnt
  

• Update GRUB to detect both Windows 10 and your Linux Mint system:

  update-grub
  

• Reinstall GRUB to your system's boot drive (usually /dev/sda, not a partition):

  grub-install /dev/sda
  

• Exit chroot and reboot your system—GRUB should now show both OS options, and your /home partition with all configurations will be intact.

第二个选项：重新安装Linux Mint，仅格式化/boot和/root分区，保留/home #

This is also a reliable approach if you'd prefer a fresh Linux root environment but keep your /home data. Here's what to do during installation:

• Boot from the Linux Mint installation media and start the setup process.
• When you reach the Installation type screen, select Something else.
• Find your existing /root partition (ext4), select it, click Change, set the Use as dropdown to Ext4 journaling file system, check the Format box, and set the Mount point to /.
• Do the same for your /boot partition (if you have one): select it, click Change, set Use as to Ext4 journaling file system, check Format, set Mount point to /boot.
• Find your /home partition, select it, click Change, set Use as to Ext4 journaling file system, do NOT check the Format box, and set the Mount point to /home.
• Proceed with the rest of the installation—your /home data and configurations will be preserved, and the new installation will set up GRUB to dual-boot with Windows 10.

无需先移除GRUB的Windows升级替代方案 #

Before you go through removing GRUB, you could try this workaround to get the Windows upgrade to complete:

• Boot into your BIOS/UEFI settings (usually by pressing F2, F10, or Del during startup on Toshiba laptops).
• Change the boot order to prioritize the Windows boot loader (it might be listed as "Windows Boot Manager" or the name of your Windows partition) over GRUB.
• Save the settings and reboot—your system should boot directly into Windows 8.1.
• Run the Windows 10 in-place upgrade tool again. Since Windows is booting directly without GRUB interfering, the upgrade might complete successfully.
• Once the upgrade is done, you can either leave Windows as the default boot or follow the GRUB rebuild steps above to restore dual-boot functionality.

Since you have Macrium images and Timeshift/BackInTime backups, you're covered if anything goes sideways—great job prepping!

备注：内容来源于stack exchange，提问作者Norris