I was running a duel boot windows 8.1 and ubuntu 14.04 when I suddenly could no longer boot my system. After booting into a live usb and run GParted I get this error:

Input/output error during read on /dev/sdb

/dev/sda contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table?

Both the primary and backup GPT tables are corrupt. Try making a fresh table, and using Parted's rescue feature to recover partitions.

Is there a way to fix this? I have tried TestDisk which won't run. Is there also a way I can backup my hard drive before I do anything that might damage my computer.

  • There's a backup GPT partition table, have you checked that?
    – teppic
    Apr 1, 2015 at 17:06
  • Both the primary and backup GPT tables are corrupt... (emphasis mine) Apr 1, 2015 at 18:25

2 Answers 2


The simplest option is to try to use the backup GPT table. This is stored automatically on the disk. The gdisk utility can do all of this for you. Simply load as normal,

# gdisk /dev/sdb

And enter the recovery and transformation menu (r), and option c to load the backup table. If it's successful you can write the correct table back out again. It won't write anything until you tell it to.

  • Both the primary and backup GPT tables are corrupt... (emphasis mine) Apr 1, 2015 at 18:25
  • Ah I misread that. Still, try gdisk as it might do a better job than parted.
    – teppic
    Apr 1, 2015 at 18:43
  • After trying what was suggested on gdisk I get the error "Caution! After loading partitions, the CRC doesn't check out!". I'm confused what is going on. If I use parted it says there is an sdb partition but fdisk says there are only sda1 and sda2 partitions. Apr 1, 2015 at 19:39
  • That's normal, you can view the loaded partition with p - and quit if it doesn't help.
    – teppic
    Apr 1, 2015 at 19:40
  • Ok so I printed the partition and I perhaps foolishly wrote the changes to the disk. I still cant find any operating system when I restart and gpart is now saying Warning! Read error 5; strange behavior now likely! Warning! Read error 5; strange behavior now likely! Partition table scan: MBR: not present BSD: not present APM: not present GPT: not present is it time to cut my losses format the hard disk and reinstall? Apr 1, 2015 at 20:00

(I know, I know not so much links, right? But hey what can I do, this man needs help!)

Hiren's BootCD might have a tool that could help.

But before you download take a look at the tools list and make up your own opinion.

As a sysadmin such a CD is always in my reach.

Here is the list of the MBR tools

MBR (Master Boot Record) Tools
Formerly BCD Editor with lots of options to configure Windows for a developer.
Boot Partition 2.60
Add Partition in the Windows NT/2000/XP Multi-boot loader.
BootFix Utility
Run this utility if you get 'Invalid system disk' message.
BootSect 6.0.6
Boot Sector Manipulation Tool, This tool replaces FixFAT.exe and FixNTFS.exe.
BootICE 2012.09.20
A boot sector manipulation utility to edit MBR/PBR/BCD.
DiskMan 4.2
All in one tool for cmos, bios, bootrecord and more.
FbInst 1.6
A tool to create universal flash boot disk that boots from all computers.
Grub4Dos installer 1.1
An universal boot loader GRUB for DOS GRLDR installer.
grub4dos 2012-10-02
An universal boot loader based on GNU GRUB, can boot off DOS/LINUX or via Windows boot manager/syslinux/lilo or from MBR/CD, builtin BIOS disk emulation.
HDHacker 1.4
Load/Save/View MBR and BootSector from a physical/logical drive.
isolinux 4.05
A boot loader for Linux/i386 that operates off ISO 9660/El Torito CD-ROMs in 'no emulation' mode.
MBRWizard 3.0.73
Directly update and modify the Master Boot Record.
MbrFix 1.3
Backup, restore and fix the boot code in the MBR.
MBR Utility 1.05
Manipulate a drive's master boot record (MBR) via the command line.
MBRWork 1.08
A utility to perform some common and uncommon MBR functions.
MBRTool 2.3.200
Backup, verify, restore, edit, refresh, remove, display, re-write and more.
BootSave and BootRest tools to save / restore MBR.
MemDisk 4.05
Allow booting legacy operating systems, floppy images, hard disk images and some ISO images.
PLoP Boot Manager 5.0.14
Boot different operating systems harddisk, floppy, CD/DVD or from USB, it can boot from an USB/CD/DVD even without BIOS support.
RMPrepUSB 2.1.620
Partition and format your USB drive and make it bootable.
Smart Boot Manager 3.7.1
A multi boot manager.
XOSL 1.1.5
A graphical boot manager that supports multi-booting of various operating systems.
  • P.S.: On a personal note, never ever just do something, because someone suggests it (I've been there, too). Don't even trust me ^^ Make up your own mind and evaluate how valuable your data is.
    – s1mmel
    Apr 10, 2015 at 15:43

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