[Workaround] 2013 ubiquity 'bug' is blocking Windows-Ubuntu migration

[Update : Leads to a casper missing feature https://bugs.launchpad.net/ubuntu/+source/casper/+bug/684280 ]

Hi folks,

I’d like to highlight a blocking with ubiquity :


Scenario :

  • Run Windows 7
  • Download 20.04 iso
  • Boot Ubuntu 20.04 toram iso with Grub4Dos
  • Ubiquity cannot release the Windows partition so partitioning is not possible.

Any idea ?

Fixing this bug opens doors to ‘2click’ Win7-Ubuntu migration

Thanks for the notification.

If it’s been a bug since 2013 then it’s hardly a blocking bug. It may be unfortunate or an inconvenience, but I’d hardly say it’s a blocker.

I suspect the process you’re going through is not common, and certainly not documented as a supported way to install Ubuntu in our official documentation.

That said, how do you reproduce this exactly. Neither the bug nor your description actually detail precise steps to reproduce it. Specifically “Boot Ubuntu 20.04 toram iso with Grub4Dos” isn’t clear, to me at least.

I agree though that resolving the various ways to install Ubuntu which may have bugs, could be useful. I’m just not convinced this is a widespread issue.

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Hi alan ,

Sorry I did not mean it was widespread and blocking a wide range of users.

I was saying “blocker” as it is keeping some people to innovate in the “Wubi” area which is getting attention right now with WIn7 EOL.

One interresting thing is that debian has this ‘toram’ Win32 loader for years and it works beautifully :


Let me explain :

  • When you want grandma to migrate to Ubuntu, she need a ‘clickclick’ solution ( No USB/iso etc…)
  • So booting the Ubuntu Iso from Windows loader is necessary
  • But you need to boot it toram and umount Windows partition to succeed partitioning which is key to success.

I understand this can be confusing

I’m still missing the specific, explicit steps to reproduce this. It needs to be step by step like

  1. put ISO in specific location,
  2. run this command,
  3. download this thing
  4. Press this button

Expected outcome: What should happen
Actual outcome: What actually happens

If you could detail that in the bug that would be helpful.

Hi alan ,

I’ve added simple steps to set up grub booting iso to reproduce the problem :


My last try is worse than the original bug reporter because I cannot force unmount the /isodevice anyway to finish partitioning.

Hope it helps!

Good news , we now are a working workaround and I succed to install a Dual Boot directly from Grub :

You have to force unmounting of the /isodevice
You also have to disconnect the loop device that points to the iso ( that is what I missed before )

After that you complete ubiquity install like of you were on USB

it seems you need more than 4GB of Ram to succeed

Where should we put the fix ? ubiquity ? some capser setup package ?

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Hi I finally marked this bug as duplicate of a 2010 casper Bug :


Which where we should work I guess.

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Hi ,

as we now exactly the problem in casper and the right way to fix it ( force umount with -d option when toram )

Could we get some help from casper maintainer on canonical side to work on ?

The patch is really simple as explained :


The umount is not enough.