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I had both ubuntu 18.04 and windows 10 on my PC, I was using grub (or grub2, can't tell now) to switch between them. I decided to reinstall ubuntu, I have chosen not to upgrade from ubuntu 18.04 to 20.04, but to fresh install ubuntu 20.04 over 18.04. So I created an ubuntu usb stick and installed from it. I do not remember my choice for boot loader destination, I think I have left this field as it was with a prompted destination. After that, the grub loader was gone, my PC booted directly into ubuntu.

I have tried:

  1. ubuntu boot-repair First I ran it with default options with no luck, then I choose advanced options - purge and reinstall grub, it finished with an error, and here is the link to the log: http://paste.ubuntu.com/p/7qvF4tCV7V/ boot-repair told me that I can post this link to a forum, so here I am.

  2. I created a windows 10 installation usb stick, tried to troubleshoot with it, but with no luck. It told me that it cannot handle the problem. here is the log: https://txt.online-reader.com/view?f=PX3sk45

Please, point me in the direction for my next actions, I am out of ideas right now.

prupru
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  • You should be able to boot into Windows via EFI-boot-menu, in Windows disabel fast-startup (hibernation) since this might be the culprit. Then boot back into Ubuntu and run sudo update-grub to see if the dual-boot is detected properly then. – mook765 Mar 21 '21 at 14:08
  • I have entered BIOS and choose to boot from legacy BIOS instead of UEFI. No luck, couldn't load anything, was told to insert a bootable drive. Switched back to UEFI in BIOS and somehow booted into windows. Now figuring out how to disable fast-startup and what's more interesting, I have no idea how to boot back into ubuntu. – prupru Mar 21 '21 at 14:33
  • Do not mix UEFI & legacy/BIOS/CSM modes. You have UEFI system with UEFI installs. Doing anything in Legacy may make things worse. Grub only boots working Windows and that includes that Windows cannot be hibernated. Fast start up sets hibernation flag. http://askubuntu.com/questions/843153/ubuntu-16-showing-windows-10-partitions & https://askubuntu.com/questions/145902/unable-to-mount-windows-ntfs-filesystem-due-to-hibernation You normally can boot Windows directly from UEFI menu when grub does not boot it. But best to have both Windows repair/recovery flash drive & Ubuntu live installer. – oldfred Mar 21 '21 at 14:52

2 Answers2

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Start the Ubuntu in the Terminal program use nano /etc/default/grub to edit the file. Change the hidden to menu and the timeout value to anything other than 0 to have a countdown of that many second before it boots the default OS. Once done the editing then sudo update-grub to have the changes written to the disk and used on next boot. You should now have the grub menu back the Ubuntu people so helpfully disabled by default...

  • I somehow booted into windows now, after switching UEFI/legacy in BIOS back and forth. Now I have to figure out how to load into ubuntu. – prupru Mar 21 '21 at 14:36
  • By doing the reverse and switching it back every time you want to boot. You have managed to install it in the wrong mode for the booting of the machine. That is the only work around for that problem unless you re-install the boot loader if possible. You do not say which way it is set to boot, but if needed you can install the Ubuntu loader in EFI mode. If windows is set to boot BIOS then I have no clue to get by that and re-install its loader to use EFI if you want this. Try the boot-repair and see if it will do it for you. https://help.ubuntu.com/community/Boot-Repair –  Mar 21 '21 at 15:24
  • I have booted from ubuntu live usb, run boot-repair, it finished with error, then I restarted and booted from hdd into ubuntu. I have changed grub setting GRUB_TIMEOUT_STYLE from hidden to menu. Now when I restart I see a blank black screen with a cursor in the left top, then boot into ubuntu. No grub menu is displayed – prupru Mar 21 '21 at 15:38
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This is the answer: Grub menu working but hidden, can't make it visible

After I set GRUB_TERMINAL=console everything started to work just fine. Hell, can't believe I wasted the whole day fixing this. Holy crackers.

prupru
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