Since karmic koala, I can't create a bootable USB. Always the same error, it arrives to 96% and then this error " checksums do not match". Also in lucid, meerkat and natty even with fresh install. Tried it with more than USB stick.

Am I doing somthing wrong? I did format the USB stick several times but no luck. It's 2Gb. Now I lost my DVD drive on my laptop, and USB is my only option. Please help!

  1. I did try different USB sticks
  2. I did try unetbootin, with success, but when booting from USB and selecting check disk for errors within the unetbootin menu it gives me 1 error, so I didn't try actually to install the O. S for precaution reasons.
  3. I did try to launch disk creator from terminal with sudo and that gives the same error on 96% of the process.

  4. doing the check proposed by chen xiao-long, the codes result no match.

    suliman@suliman-laptop:~$ sudo mount -o loop /home/suliman/Documents/ubuntu-11.04-desktop-i386.iso /mnt
    [sudo] password for suliman: 
    suliman@suliman-laptop:~$ md5sum /mnt/casper/filesystem.squashfs
    174bb50daab963e681d2dcd9603f737b  /mnt/casper/filesystem.squashfs
    suliman@suliman-laptop:~$ md5sum '/media/8BE1-C58A/casper/filesystem.squashfs' 
    e4129f8ff21860d978c911b3b394f807  /media/8BE1-C58A/casper/filesystem.squashfs
  5. if the usb port is faulty, how can i check that?


Using a Kingston 4GB Data Traveler USB stick I was getting the same checksum error.

Then as Jordon Bedwell (above) suggested I dropped the persistence file from 1GB down to 256MB and it went through without a hitch; or the checksum error popping up.

Used USB Startup Disk Creator from the menu. Using Ubuntu 10.04 LTS to make a 11.04 USB.

Thanks Jordon


problem solved, but no answer to the question. i used unetbootin with success but the problem with ubuntu disk creator remains.

  • did you try another storage device?
    – dsaint
    May 27 '11 at 15:33
  • yes , i did try.
    – suli8
    May 27 '11 at 15:38

I removed the usb-creator-gtk, rebooted, reinstalled it, deleted the partition on the usb drive using disk utility, created new partition and attempted using usb-creator-gtk again with success. Not sure which of the steps above actually resolved the problem.


The installer iso file might be corrupted. Therefore, you should check the .iso file with md5sum before creating a bootable usb.

Check the iso file:

md5sum ubuntu_iso_file.iso

Then compare the output with the original ones in the official site.

  • i did that on the last one 11.04. it was ok, they match. and it did happened with every iso i downloaded.
    – suli8
    May 1 '11 at 15:16
  • i did. nothing helps. i don't know what else to do
    – suli8
    May 4 '11 at 11:38
  • did you try with a different usb stick?
    – Coldfish
    May 4 '11 at 13:25
  • yes. it is in the question itself. i tried 3 differnet ones.
    – suli8
    May 20 '11 at 22:44
  • did you use start up disk creator or unetbootin? unetboot in is available in synaptics and worked better for me.
    – dago
    May 20 '11 at 23:09

I'd suggest using Unetbootin. When the CD is copied to your USB drive, the syslinux bootloader has to be installed to it, rather than isolinux from the CD. The different files on the USB drive compared to the CD probably caused the problem when you selected the disk checking option.

The main thing to check is that the md5sum of the /casper/filesystem.squashfs file on your USB drive is the same as that file on the ISO. All the other files are just "helper" files that allow the USB drive to boot. They aren't used during or after the install.

To check that the md5sums are the same, you can run

sudo mount -o loop /path/to/ubuntu.iso /mnt
md5sum /mnt/casper/filesystem.squashfs
md5sum /path/to/USB/casper/filesystem.squashfs

and then make sure that the outputs are the same.

  • now , using this method the md5sums does not match.
    – suli8
    May 22 '11 at 10:19
  • That's very strange. I've had a similar problem before, but that was on an old computer with a failed USB port. Since you've tried multiple USB sticks, there's probably something wrong with the computer itself. May 22 '11 at 12:47
  • i have 4 usb ports, and all working as recognizing devices and data transfer. how can i be sure that it is the usb that is faulty?
    – suli8
    May 22 '11 at 18:25
  • I'm not sure how to check if the USB ports are faulty. Maybe someone else can help here? I can't think of any other reason why the checksums would be different... May 22 '11 at 18:49

Disable the reserved storage or make it under 500MB.

  • How do you "disable the reserved storage"?
    – Florian F
    Jan 1 at 1:21

I landed how to check this. I followed these instructions and my downloaded image seems to pass, but the tool won't work with it. I believe the Startup Disk Creator has a problem, so I am going to use another see if it works.

Here are the commands:

gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys "8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092" "C598 6B4F 1257 FFA8 6632 CBA7 4618 1433 FBB7 5451"
gpg --list-keys --with-fingerprint 0xFBB75451 0xEFE21092
gpg --verify SHA256SUMS.gpg SHA256SUMS
sha256sum -c SHA256SUMS 2>&1 | grep OK

And below the output:

sha256sum -c SHA256SUMS 2>&1 | grep OK
ubuntu-16.04-desktop-amd64.iso: OK

Remember to put the files in the same directory as the downloaded iso.

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