I have 3 partitions on my computer.

|  Device   |  Type |   Size   |  Used   |                                                 Comments                                                 |
| /dev/sda1 | ntfs  | 104MB    | 35MB    | This is Windows loader                                                                                   |
| /dev/sda2 | ntfs  | 144598MB | 64536MB | Here I want to install UBUNTU                                                                            |
| /dev/sda3 | ntfs  | 105353MB | 20227MB | This my backup partition. I don't want to delete anything from here, I have all my necessary information |

The problem is when I select "Device for boot loader installation" /dev/sda2.

I get:

No root file system is defined.
Please correct this from the partitioning menu.

How can I resolve this?


3 Answers 3


The complaining is that you have not defined which will be the "/" (= root partition).

Look at this image and pay attention at the "Mount Point":

enter image description here

  • Ok. But doing this I don't lose my backup partition, no?
    – Emilio
    May 9, 2012 at 1:16
  • 2
    I don't care of Windows. I want to only have Ubuntu
    – Emilio
    May 9, 2012 at 1:18
  • 1
    You don't need to select a "/boot" path but you must select "/" path . As you say in you question that should be /dev/sda2
    – desgua
    May 9, 2012 at 1:33
  • 2
    Also the boot loader install should be /dev/sda not /dev/sda2
    – desgua
    May 9, 2012 at 1:38
  • 2
    Do not touch /dev/sda3 that is your backup and you should be fine. But I would also make a backup in an external media "just in case"...
    – desgua
    May 9, 2012 at 1:39

Make sure that the partition file system you wish to install Linux, Ubuntu or Backtrack on it is ext4, ext3 or ext2, and not FAT32 or NTFS.

Then mount / on it:

  1. During the installation process press "change" on the partition you wish to use

  2. Make sure "do not use this partition" scroll is not chosen, scroll to ext4, ext3 or ext2

  3. On the "mount" field write /

  4. Click ok, then next a message will appear saying something like "swap area was not defined, do you wish to continue or choose a swap area?", click "ok" and continue or click "go back" and choose another partition and click change, on the file system scroll choose "swap" and click "ok" and next

This will solve both "no root file system is defined" and the "swap area" message, if you still get the swap area message then on step 4 mount /swap to the partition

  • 1
    Newer versions of Ubuntu use a swap file instead of a swap partition.
    – mchid
    Feb 11, 2020 at 9:14
  • The mount point / and selecting swap space helped to complete the installation successfully.
    – Shamsher
    Jul 2, 2020 at 15:33

Make sure the extension is either:

ext2, ext3 or ext4 but i'd recommend you select ext4-journouling file system. The mount point is in /


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