When installing ubuntu in dual boot,full hard disk is shown without windows partitions

Even if you were following the correct steps of installing ubuntu along side with windows,there is a possibility that, at the installation type window, you are shown the whole hard disk instead of the hard drive with windows partition like the figure below.

 

  

or if you were trying to install only ubuntu,you may have warned that,

 

Then you are having this problem that I'm addressing here.

This happens mainly because if you had Windows 8,it is in UEFI mode with gpt partitions, and then if you are reinstalling like Windows 10 in BIOS boot mode,  Windows DOES NOT correctly convert from gpt to MBR(msdos). It leaves backup gpt table.  

The main problem here is even though you have some gpt left in your hard disk,if you check hard drive from windows (from disk manager's properties or from command prompt) it does not show you that.

 

 But trust me you have some gpt left overs at your hard drive and it's what's causing problems.

Solution is simple :

Even though you can do it from windows cmd prompt or convert everything to gpt and use uefi boot mode as well,this is the easiest way that I prefer.

Warning :  Even though we are going to keep MBR data untouched,it is recommended to keep a back up of your important files.

1) If you  have windows and going to install ubuntu along side

*  Use a bootable  ubuntu and follow normal procedure and go to 'try ubuntu' option

* Then open the terminal from there, type gdisk /dev/sda (or /dev/sdb or whatever necesarry to access your hard drive)

(

 

you would be most probably be said that GPT is also present and ask 

'Found valid MBR and GPT. Which do you want to use?'

Here your choice is irrelevant,so choose whatever you want. )

* Then enter expert's menu by typing x  at terminal 

* Then type z  to zap GPT

* y  to confirm saying 'yes'

* Blank out MBR? (Y/N):  type n  to keep MBR data untouched

So now your problem is solved!!!

2) If you have installed only ubuntu and want to remove corrupted GPT partition table

There is an efi partition that you were asked to create when installing ubuntu because ubuntu found corrupted GPT partition table. So converting whole hard disk to MBR means that your going to LOOSE parts of ubuntu kernel !!!

If your only concern is removing corrupted GPT partition table then you can follow same above steps and at the end you would be told,

 

You are done and do not have to anything about that message.