I have an old HDD (GPT) with Win 10 and Ubuntu 20.04. I added an SSD (GPT) with Windows 10 and Ubuntu 22.04. I unplugged the old HDD before I installed the SSD. What do I need to do to safely get Grub2 on the SSD to show all four boot options? No UEFI available. I boot in MBR mode (bios only) and load the OSs in GPT through Grub2. In case you ask, I use USBs to boot the Windows GPT partitions, and Grub2 finds them fine.

In summary:

  • HDD (GPT) dual-boot with Win 10 and Ubuntu 20.04 LTS
  • SSD (GPT) dual-boot with Win 10 and Ubuntu 22.04 LTS
  • Bios Only mobo
  • USBs that boot both Windows 10 OSs in GPT, and they get found by Grub2 on each disk
  • Removed HDD, installed dual-boot on SSD
  • HDD still not plugged in
  • SSD boots Win 10 and Ubuntu 22.04 fine.
  • Did you run sudo update-grub with os-prober on. Grub 2.06 may turn os-prober off and you should turn it off once it runs and manually add boot stanzas to 40_custom. Some security issue with os-prober opening every partition looking for installs. BIOS only with Windows 10 & GPT unusual. Please copy & paste the pastebin link to the BootInfo summary report ( do not post report), do not run the auto fix till reviewed. Use often updated ppa version over somewhat older ISO with your USB installer or any working install. help.ubuntu.com/community/Boot-Repair
    – oldfred
    Jan 17, 2023 at 19:12
  • "...manually add boot stanzas to 40_custom?" Not sure what you mean—Grub would detect the stanzas, right? Second, Do you want the HDD Pastebin or the SSD Pastebin? I haven't reconnected the old HDD yet.
    – salmmus
    Jan 17, 2023 at 19:30
  • Better with both, but if duplicate UUIDs that will not work. First thing I do is backup grub.cfg, and turn off os-prober. Then add whatever boot stanzas I want into grub's 40_custom. You then can rename an entry if desired, so you can tell which Ubuntu you are booting. I have multiple installs and have to do that and have old installs, not yet deleted that I do not want in grub menu. And without os-prober scanning all my partitions, updated to grub.cfg are a lot faster. askubuntu.com/questions/659528/…
    – oldfred
    Jan 17, 2023 at 21:42
  • Here's the HDD Pastebin. I figure we need to fix this first. It shows Grub2 detected the actual Windows 10 OS on the HDD and the Windows 10 boot USB. But selecting the HDD option causes a boot loop because it can't boot from GPT, which is where the USB booting comes into play.
    – salmmus
    Jan 18, 2023 at 13:24
  • Pastebin: "BIOS/UEFI firmware: V17.17(8.15) from American Megatrends Inc. The firmware is EFI-compatible, but this installed-session is in Legacy/BIOS/CSM mode (not in EFI mode)." Not sure why it says that because there are no UEFI options in bios. Just FYI.
    – salmmus
    Jan 18, 2023 at 13:54


You must log in to answer this question.

Browse other questions tagged .