Hyper-V VM not starting

Question

I have a host that lost power. Now my Hyper-v VM is not starting. I get the following error:

failed to power on with error 'then chain of virtual hard disk is inaccessible. there was an error opening a virtual hard disk further up the chain

The chain of virtual hard disks is corrupted. There is a mismatch in the identifiers of the parent virtual hard disk and differencing disk.

Any help would be appreciated.
Thanks

Answer 1

Hi,

It seems the virtual disk is corrupted. Please click Inspect Disk in the Actions pane of the Hyper-V Manager and select the last avhdx file, then click Inspect Parent to identify the order of the differencing disks. Since the chain is already corrupted, you may have to guess the order based on file size, last modified time, etc. After that you can try merging the differencing disks manually and see if the VM can start with the merged disk. Refer to the below link for the detailed steps of merging the virtual disk files. Please remember to back up your virtual disk files before any operation.

https://social.technet.microsoft.com/wiki/contents/articles/6257.manually-merge-avhd-to-vhd-in-hyper-v.aspx

Best Regards,
Ian Xue

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Answer 2

Hello

Thank you for your question and reaching out. I can understand you are having issues related to Hyper-V VM.

1. Make a copy/backup of your base vhd, just in case :)
2. In the settings of the virtual machine, locate the IDE controller where your disk is connected and click "Inspect" on the VHD.
3. On next popup you will get the possibility to "reconnect" the broken virtual hard disk chain.
4. Next
5. Locate your base vhd, mark "ignore id mismatch" , next.

I found these steps from below similar thread as yours.

https://social.technet.microsoft.com/Forums/en-US/87656df8-0a10-4915-8621-49f17f0cb985/hyperv-w8-there-was-an-error-opening-a-virtual-hard-disk-further-up-the-chain?forum=winserverhyperv

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