[Solved] Windows 10 pro - BOOTMGR is missing

[janpeter]

Hi

The other day I tried to extend the virtual hard disk which was difficult since I could see how to make the new area contiguous with the C area. I made the misstake to make C-area active, despite warnings. Now I cannot boot and get the message "BOOTMGR is missing”.

I understand that I can download the Windows 10 media creation tool on a USB-stick.
Then I guess I can use that to repair my virtual hard disk. But what the steps to do here?

Under Settings/System for the VM I find the boot order, but cannot find USB-stick. What should I choose here?

My idea is to use some “repair” functionality of the media creation tool from Windows.
There are several older youtube videos on this subject and guess it should be doable.
If there not is some even simpler workaround.

By the way I do have a well functioning clone of Windows 10 pro. Simple would be to use the terminal there and try to repair the other virtual disk. Is that possible?

Thanks

[Martin]

You can use the Media Creation Tool to create an ISO file and use this in the virtual DVD drive to boot the broken VM.

[janpeter]

Sound good! Would appreciate some more details. Should I boot from the MCT- file? How should I connect it to the "corrupt" virtual machine? I guess Settings/System or Settings/Storage or both should be set right.

Thanks

[Martin]

Just select "ISO file" instead of "USB flash drive" when using the MCT to create the "installation media for another PC"

[janpeter]

But how to connect the ISO-file to my corrupt VM? Or should I not do that and try to boot from the corrupt VM?

[mpack]

Your VM is not corrupt. The hard disk filesystem used by the guest OS may be corrupted, but that has yet to be proved and is very different from a corrupt VM, which would be the result of host damage.

In any case the effect of this guest OS problem is that you can't boot from the hard disk. Not a problem if you intend to boot from a CD (or ISO).

[janpeter]

I understand it is not the VM that is corrupt, but the virtual HD for the VM that contains System, C, and Recovery partitions.
The problem is that the C-partition I made "active" under Windows 10 (and a misstake) and should just be "un done".

But I feel I need a little bit more instruction from you (mpack, Martin, or someone else).

1) Should I somehow connect the ISO-file from downloaded MCT to the VM that use the "corrupt" virtual HD?
If so how?
2) If I should not connect the ISO-file what should I then do?

Thanks!

[mpack]

You attach a CD/ISO the same way you always do, i.e. using the Storage panel of the VM settings. See section 3.7 of the user manual.

[janpeter]

So I understand the advice as something like:

1) Make a MCT iso-file using the standard download procedure from Microsoft

2) Mount it to the existing VM that does not boot as a virtual optical disk

3) Check that the Setting/System has a boot order where optical is ticked (and before hard disk)
and seems to be by default

4) Start the VM and now it should boot using the boot sector on the mounted virtual optical disk

5) And now comes the new challenge. In my eyes I need to go to Windows Disk Manager as described in my in
my related post viewtopic.php?f=2&t=86016

a) Here I now might be able to simply make partition "System" active again instead of C - or maybe not?

b) An alternative approach would be to try to start up the repair functionality that Windows has
and is shown in numerous youtube videos, but these are aimed for real and not virtual machines
and where the repair option come up at start when booting from the external physical DVD.

Perhaps I really get option b) when booting the virtual machine at 4)?

Or what?

[janpeter]

HI again,

I just want to report that the issue is solved. Got some partial help from Microsoft without paying.

https://support.microsoft.com/en-us/hel ... tup-issues

But the work needed some more. I did the following steps:

1) Attached the MCT iso-file as optical virtual disk to the VM that did not boot.

2) I am asked if I want to re-install Windows ... and I am not but, first after pressing NEXT
you get the choice to start repair....

3) Several choices here and I chose in the end Command-windows

4) Here I run bootrec.exe /ScanOS
Then I got confirmed that my Windows is still there

5) Then I run DISKPART
This is a powerful tool for changing the (virtual) disk.
Do ? to get a list of commands

Here I now write VOLUME=1
Then PARTITION=1
Then ACTIVE

Now the small System Partition is active again.

I do exit from DISKPART and then exit from command window

6) Turn the computer off from the repair menu

7) Restart the VM and just let it boot.

Once up and running again - I take a look with the graphical Disk Manager and see that indeed
I have partition System Reserved active and C: inactive, and back to normal.

The third partition is a Healthy (Recovery Partition) and stands in the way for
simple extension of the hard disk that was the original problem and documented in another thread.

Hope this may help someone else!

Thanks

[mpack]

Thanks for reporting back.