Azure Virtual Machines
An Azure service that is used to provision Windows and Linux virtual machines.
Azure VM OS corruption after disk resize – need recovery steps
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Amrit Jaiswal
5
Reputation points
Hello All,
I have a Windows VM where I attempted to increase the disk size from 2 TB to 3 TB without taking a snapshot beforehand. After resizing, I’m now unable to connect via RDP, and the VM Agent version is not visible. The OS appears to be corrupt, and the boot diagnostics show a BCD error with error code 0xc00000f.
I have already tried redeploying, rebooting, and attaching the corrupted OS disk as a data disk to another VM to rebuild the BCD, but the issue remains unresolved.
Could you please suggest the best way forward?
Azure Virtual Machines
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Nikhil Duserla 9,355 Reputation points Microsoft External Staff Moderator2025-07-16T19:36:00.5666667+00:00 Hello @Amrit Jaiswal,
Error- File: \Boot\BCD Status: 0xc000000f Info: The Boot Configuration Data for your PC is missing or contains errros.
This issue occurs when one of following conditions is true:
- The Boot Configuration Data (BCD) is corrupted.
- The reference to DEVICE and OSDEVICE on the boot configuration data is missing or unknown.
- The binary displayed on the screenshot (other than winload.exe or \boot\BCD) is missing from the operating system disk.
Please refer to this link for resolution- https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/boot-error-0xc000000f#resolution-for-error-1-and-error-2
If you have any further queries, do let us know.
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Amrit Jaiswal 5 Reputation points
2025-07-17T19:48:43.5966667+00:00 Thank you for the response. I have followed all the steps you shared, but unfortunately, they did not work.
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Amrit Jaiswal 5 Reputation points2025-07-17T19:59:42.78+00:00 Please follow this steps:
- Created a new Azure virtual machine and attached the corrupted OS disk to it as a data disk.
Opened the Azure Portal, navigated to the newly created VM, and selected Run command from the left-hand menu.
Under Operations → Run command → RunPowerShellScript, executed the following command to rebuild the BCD for a Generation 1 (BIOS-based) VM:
powershell Copy bcdboot F:\Windows /s F: /f BIOSAfter successfully rebuilding the BCD, detached the repaired disk from the troubleshooting VM.
Reattached it as the OS disk to the original VM.
- Started the original VM — it should now boot properly if the issue was related to a corrupt or missing BCD.
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