I had a problem with a virtual machine at boot; have read that I can attach operating system disk to another virtual machine (as data disk) and change some keys on registry to start in safe mode.

I don't understand one thing: I have, as resource, a "disk", that isn't a vhd, so I haven't the possibility to see it in the procedure to attach the disk to the other vm; how to make the "disk" a vhd or however visible so I can attach?

This is what I see as reosurce:

Azure disk type virtual machine not working

  • To do this you'll have to spin up another working virtual machine that is able to see and mount this "disk" the same way as the original VM did. I can't help you anyway as I didn't even tried Azure for the first free 30 days. :) – Marco Oct 12 '17 at 13:36
  • There are 2 methods: the first is to create a new virtual machine with that disk, I tried it but it doesn't work, so I want to attach the os faulty disk to another virtual machine, change some keys in the registry, detach the disk and create a virtual machine with that disk to start in safe mode. – Marco Mangiante Oct 12 '17 at 13:41
  • Well, you'll either learn how to do it, or pay a professional to do it for you! – Marco Oct 12 '17 at 13:42
  • I don't know how to use the disk because it is not a vhd disk, that's the issue: if you want attach a disk you must use a vhd, but mine is not seen as vhd. – Marco Mangiante Oct 12 '17 at 13:49

First you need a Virtual Machine that is using managed disks. From the picture, I can see that is a managed disk, hence, you can only attach these types of disks to VMs in that format.

You can convert your current VM to that format:


or build a new VM using managed disks, and then attach a new disk to it:


  • Thanks Bruno, yesterday I googled and found many of info that you shared in your reply. I also found a script (but still not tested) that convert a managed disk to vhd, but as you suggest, is more simple to start a new VM using managed disks and then attach the other. – Marco Mangiante Oct 13 '17 at 6:21
  • great! if you think the information I provided answer the question, please kindly accept it as an answer. cheers – Bruno Faria Oct 17 '17 at 0:38

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