Fedora Linux Support Community & Resources Center

Go Back   FedoraForum.org > Fedora Resources > Guides & Solutions (Not For Questions)
FedoraForum Search

Forgot Password? Join Us!

Guides & Solutions (Not For Questions) Post your guides here (No links to Blogs accepted). You can also append your comments/questions to a guide, but don't start a new thread to ask a question. Use another forum for that.

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 20th December 2015, 09:45 PM
Jeff72 Offline
Registered User
 
Join Date: Nov 2008
Posts: 175
windows_98_nt_2000chrome
grub rescue> Boot fails: Example commands to boot+fix Windows 10 + Linux dual boot

grub rescue> Boot fails: Example "grub rescue" commands to boot and fix (Windows 10 update broke Windows 10 + Linux dual boot):
--------------------------------------------------------------------------------------------------------------==---------------
Explanation:
------------
Windows 10 "Upgrade to Windows 10 Home, version 1511, 10586" (sent out in November/December 2015) creates an additional Windows partition and can break grub2 from booting a dual boot Windows 10 and Linux system.

The example below has hd0 as the primary boot hard drive. Windows was originally on the first partition, with linux /boot on the 2nd partition, and the rest of the Linux LVM partition(s) on 3rd partition.

The example below was using the following partitions setup prior to applying "Upgrade to Windows 10 Home, version 1511, 10586":
-------------------------------------------------------------------------------------------------------------------------------
Dual boot Windows 10 and Fedora Linux system
Before Windows 10 1511, 10586 upgrade:
Partition 1 (hd0,msdos1) Windows primary partition
Partition 2 (hd0,msdos2) Linux /boot partition
Partition 3 (hd0,msdos3) Linux LVM partition (/ and possibly other partitions)

Windows 10 "Upgrade to Windows 10 Home, version 1511, 10586" created a new partition right after partition 1, between partition 1 and 2, which created the following:
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
Partition 1 (hd0,msdos1) Windows primary partition
Partition 2 (hd0,msdos2) Windows rescue/upgrade/whatever partition
Partition 3 (hd0,msdos3) Linux /boot partition
Partition 4 (hd0,msdos4) Linux LVM / and other partition(s)
etc...

So, Windows 10 "Upgrade to Windows 10 Home, version 1511, 10586" breaks grub2 because boot block grub2 still thinks it should boot grub2 from (hd0,msdos2) when it now needs to boot from (hd0,msdos3).

Also NOTE: You may have to disable "Secure Boot" in BIOS to allow Linux to boot. Windows may re-enable "Secure Boot" with this upgrade 1511.
----------------------------------------------------------------------------------------------------------------------------------------------

Output you see on boot after starting to install Microsoft "Upgrade to Windows 10 Home, version 1511, 10586"
---------------------------------------------------------------------------------------------------
.
error: unknown filesystem.
Entering rescue mode...
grub rescue>

Show current partitions:
------------------------
grub rescue> ls
(hd0) (hd0,msdos4) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1) (hd1) (hd1,msdos1)

Notes, for above example:
-------------------------
(hd0) is hard drive 0
(hd1) is hard drive 1
(hd0,msdos4) is hard drive 0 partition 4
(hd0,msdos3) is hard drive 0 partition 3
(hd0,msdos2) is hard drive 0 partition 2
(hd0,msdos1) is hard drive 0 partition 1
(hd1,msdos1) is hard drive 1 partition 1
etc...

Show current grub boot settings:
--------------------------------
grub rescue> set
prefix=(hd0,msdos2)/grub2
root=hd0,msdos2

Notes for above example:
------------------------
prefix = location of your /boot partition and path to /boot/grub2 directory (while being in /boot, so just /grub2)
root = location of your /boot partition

Find your current /boot partition containing /boot/grub2 (for example, you want the directory containing grub.cfg):
-------------------------------------------------------------------------------------------------------------------
grub rescue> ls (hd0,msdos2)/grub2
error: unknown filesystem.

grub rescue> ls (hd0,msdos1)/grub2
error: unknown filesystem.

grub rescue> ls (hd0,msdos4)/grub2
error: unknown filesystem.

grub rescue> ls (hd0,msdos3)/grub2
./ ../ grubenv themes/ device.map i386-pc/ locale/ fonds/ grub.cfg

Success, we see grub.cfg on the msdos3 partition now, so our new /boot partition is (hd0,msdos3)

Change current boot grub settings to use correct partition:
-----------------------------------------------------------
grub rescue> set prefix=(hd0,msdos3)/grub2
grub rescue> set root=hd0,msdos3

Verify new settings are pointing to your new grub2 partition:
-------------------------------------------------------------
grub rescue> set
prefix=(hd0,msdos3)/grub2
root=hd0,msdos3

Start grub2 back to "normal" and get the grub boot menu with new grub2 partition settings:
------------------------------------------------------------------------------------------
grub rescue> insmod normal
grub rescue> normal

You should now see the normal grub boot menu, including a boot timer.
Quickly select your Linux boot option and boot Linux, before the system boots Windows (if Windows is your default boot).
NOTE: You need to boot linux to make the new grub settings permanent for future system boots.

After logging into Linux:
Open a command line, then run the following to save settings on boot:
NOTE: This is assuming your Linux boot drive is /dev/sda
(To verify your Linux boot drive, run df /boot and look at the /dev/sd? setting for your system.)
--------------------------------------------------------------------------------------------------------------
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
sudo grub2-install /dev/sda

Your system should now be reconfigured to boot with your active partition table, using the new partition number for your Linux /boot partition.

Test your systems boot with:
sudo reboot

NOTE: When you next boot to Windows 10, Windows 10 will continue with it's upgrade (mine was at 30% complete) and will reboot at least one more time to finish the Upgrade to Windows 10 1511.
Reply With Quote
  #2  
Old 3rd May 2016, 07:49 AM
LinuxBlue Offline
Registered User
 
Join Date: Jan 2013
Location: Australia
Posts: 42
linuxsafari
Re: grub rescue> Boot fails: Example commands to boot+fix Windows 10 + Linux dual boo

I had same trouble and easy fix was to get "Ultimate boot CD" which has boot recovey on it. It got me back up and running when nothing else worked. It is easy to use and works! Solved my problems fast and saved the trouble of re installing fedroa when disk failed to boot and just gave me "Grub rescue> prompt"
Reply With Quote
  #3  
Old 31st May 2016, 09:12 AM
jimbim1 Offline
Registered User
 
Join Date: May 2016
Location: London
Posts: 1
linuxfedorafirefox
Re: grub rescue> Boot fails: Example commands to boot+fix Windows 10 + Linux dual boo

Had similar issue with win7, 8 and 8.1 and found this article helpful:
http://twomorecents.com/cant-boot-li...as-taken-over/
Reply With Quote
  #4  
Old 16th December 2016, 04:47 PM
mebrex Offline
Registered User
 
Join Date: Dec 2016
Location: Italy
Posts: 1
windows_98_nt_2000chrome
Arrow Re: grub rescue> Boot fails: Example commands to boot+fix Windows 10 + Linux dual boo

my partitions are not msdos, they are gpt. therefore the ls command lists the following:
grub rescue>(hd0) (hd0,gpt8) (hd0,gpt7) (hd0,gpt6) (hd0,gpt5) (hd0,gpt4) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1)

here is out put of set
grub rescue>set
prefix=(hd0,gpt7)/boot/grub
root=hd0,gpt

I think Ubuntu 12.04 uses grub2 bootloader but here set results grub. does it mean ubuntu is deleted?

I try to find my current /boot partition and typing the following results:

grub rescue>(hd0,gpt7)/boot/grub (i tried with all gpt 1,2..8)
err: unknown file system

I desperately tried different paths , but nothing found containing grub.cfg

I Installed ubuntu 12.04 alongside windows8 then updated to windows 10 in December 2015. windows is in UEFI mode and I installed ubuntu in Legacy BIOS mode in my acer machine. Windows 10 has been updated many times since then I dont remember the last time i used my ubuntu os.
now I try to Install it from a USB ISO file and it says no OS detected in this machine .

I am almost novice to ubuntu and I appreciate your help guys!

Last edited by mebrex; 16th December 2016 at 05:25 PM.
Reply With Quote
  #5  
Old 17th December 2016, 02:34 PM
nobody Offline
Registered User
 
Join Date: Mar 2012
Location: München, Deutschland
Posts: 840
windows_98_nt_2000chrome
Wink Re: grub rescue> Boot fails: Example commands to boot+fix Windows 10 + Linux dual boo

http://forums.fedoraforum.org/showthread.php?p=1777611

_nobody_
__________________
I am nobody, and nobody is perfect, therefore I am perfect!
Reply With Quote
Reply

Tags
boot, commands, dual, fails, fix, grub, linux, rescue&gt, rescue>, windows

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
dual boot with xp issue - grub can't boot into windows JohnRock Installation, Upgrades and Live Media 7 10th January 2010 02:26 AM
Boot Failure w Grub installed to non-MBR partition w/Windows 7 dual boot kamikazepipes Installation, Upgrades and Live Media 14 3rd January 2010 12:19 AM
Grub fails to boot Vista in an F8-Vista dual boot kpfuser Installation, Upgrades and Live Media 2 2nd May 2008 02:57 PM
Dual-Boot Linux and Windows XP with GRUB on SATA debudayan Installation, Upgrades and Live Media 2 31st July 2007 06:17 PM
Dual Boot probl Win XP and FC 3: no boot menu and automatical boot to windows siwask Installation, Upgrades and Live Media 1 18th February 2005 03:57 AM


Current GMT-time: 12:32 (Wednesday, 26-07-2017)

TopSubscribe to XML RSS for all Threads in all ForumsFedoraForumDotOrg Archive
logo

All trademarks, and forum posts in this site are property of their respective owner(s).
FedoraForum.org is privately owned and is not directly sponsored by the Fedora Project or Red Hat, Inc.

Privacy Policy | Term of Use | Posting Guidelines | Archive | Contact Us | Founding Members

Powered by vBulletin® Copyright ©2000 - 2012, vBulletin Solutions, Inc.

FedoraForum is Powered by RedHat