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/dev/sda contains GPT signatures indicating that it has a GPT table. However, it has a fake msdos partition table as it should. Perhaps it was corrupted? Is this a GPT partition table?

So, that's the error message and this is during my first OS install of Ubuntu. Can close the message box. Can't click yes and can't click no. What do I do?

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Could you provide the error message that you received? –  Kevin Bowen Jan 31 '13 at 4:19
just says i may have deleted the table or a program may have corrupted it for me –  user127455 Jan 31 '13 at 4:39
The error message you reported makes no sense, because the two conditions (GPT signature present and "fake" MS-DOS table) are in fact consistent with a valid GPT disk. I therefore suspect you've omitted a "not" or "doesn't" somewhere. Please check again. –  Rod Smith Jan 31 '13 at 23:31

3 Answers 3

up vote 0 down vote accepted

I've seen a similar problem on my disk when I had a leftover partition from my windows 7 system. Went back to windows 7, and took all the partitions off using disk manager.

Also, make sure the disk is not "dynamic" in disk manager.

After that, I was able to do a clean install of ubuntu 12.1o :)

In case you don't have a system running windows 7, you can boot with a windows 7 dvd and run setup. Choose "advanced" when you get to choosing partition for the installation, and erase all partitions there.

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I am answering because the answers here are inadequate. I don't want future viewers of this question to destroy their windows partitions just to install Ubuntu.

To fix your problem, follow these steps:

  1. Boot the emergency disk and open a text-mode shell.
  2. Type gdisk /dev/sda (change /dev/sda to whatever is appropriate to access your hard disk, if necessary). The program is likely to complain that it's found both MBR and GPT data, and will ask which to use. It doesn't matter which you tell it to use.
  3. At the Command prompt, type x to enter the experts' menu.
  4. At the Expert command prompt, type z to zap (destroy) the GPT data.
  5. Type y in response to the confirmation about destroying the GPT.
  6. Type n in response to the query about blanking the MBR. Caution: If you answer y here, you'll destroy your Windows partition(s)!
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Jesus Christ, thank you! –  Joe Jun 22 '14 at 4:13
Same as above! jaja You saved me man! Thanks! –  Pablo Aug 8 '14 at 23:16
Obviously, this should be the accepted answer. –  w0lf Mar 6 at 14:39
"The program 'gdisk' is currently not installed" Please let me know what to do? –  shan Apr 5 at 6:01
Everyone who has Windows 8 in UEFI mode with gpt partitions and then reinstalls Windows in BIOS boot mode has this issue. Windows does not correctly convert from gpt to MBR(msdos). It leave backup gpt table. Better to use fixparts as a bit easier, but gdisk is good. Or better still just install Windows in UEFI mode, you may have to modify installer slighter if older version of Windows to have it work in UEFI mode. rodsbooks.com/fixparts –  oldfred Apr 9 at 19:42

I do not know why, however if this is a fresh install without ANY data being retained on the HDD boot up as the livecd then use gparted to clear the GPT table and make an msdos partition table.

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can i do this on windows 7? –  user127455 Jan 31 '13 at 4:14

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