Grub rescue> mode after installing endless-OS

english install
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Huge thanks to @Pranav_Modem for spending a lot of time working with me to help understand how this problem happens, and how best to fix affected machines. I hope to release a new version of the Endless Installer that fixes the original bug, but that won’t help you if your system is already in this state.

The best way to recover is as follows:

  • On another Windows computer, create an Endless USB stick.
  • It will contain a folder called endless, containing a folder called grub, containing a file called grub.cfg. (Depending on your configuration, the .cfg part may be hidden.)
  • Download this new grub.cfg and save it to the USB stick, replacing the existing grub.cfg.
  • Start your computer from the USB stick. It should now present you a GRUB menu with an option to boot Windows from your hard disk.
  • Find the endless-installer.exe you used to install Endless OS – again, the .exe part may not be shown – and rename it to endless-uninstaller.exe.
  • Run it – it should uninstall the Endless OS bootloader and put the Windows one back.

If you have adjusted the bootable flag on your system drive using the Disks application in Endless OS, you may not get a Windows entry in the GRUB menu. You’ll have to make sure it’s back how it was originally for this to work. It is normally set on the smaller NTFS partition towards the start of the disk.

If you’re interested: the problem seems to be that the installer gets into an inconsistent state where Endless OS has actually been installed, but it presents an error message. Retrying the installation – as suggested by the error message – causes the installer to remove most of Endless OS from your C: drive, but it leaves the Endless OS bootloader installed. The bootloader can’t function without the parts installed on your C: drive, so it shows this rescue prompt.

For advanced users who have a USB stick for Windows or another Linux distribution: the steps above are just a way to reinstall Windows’ MBR on the system disk. If you can boot into Windows another way, you can fix it manually without running the Endless OS uninstaller; if you have a live USB for another Linux distribution, you may be able to use the ms-sys tool to reinstall the Windows MBR.

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