Mistake 0x0000007B (INACCESSABLE_BOOT_DEVICE) Indicates on computer startup that Windows cannot access the boot drive because a required driver is missing or the disk is corrupt.
an administrator may encounter 0x0000007B error in the following cases
- When you restore Windows from a backup to another physical computer or Hyper-V, VMware, or VirtualBox virtual machine (or other hardware in bare metal recovery scenarios);
- during P2V or V2V migration;
- after moving (cloning) Windows to a new hard drive or computer;
- If you are using a Windows image to migrate a physical machine (for example, using disk2vhd) and deploying a new virtual machine from that VHD image;
- after switching the SATA controller mode in the BIOS from AHCI to IDE/RAID or vice versa (in this case, simply open the BIOS settings and restore the original SATA settings);
- when replacing the motherboard and/or hard disk controller;
- After BIOS/UEFI firmware is updated or settings are changed.
Stop error 0x0000007B after converting physical host to virtual machine
Typically, I encountered error 0x7b after converting a physical computer running Windows Server 2008 R2 or Windows 7 to a virtual machine using VMware vCenter Converter. After the conversion is complete, Windows will not boot on the new VM and a BSOD (Blue Screen of Death) will appear on the screen with a stop code:
STOP: 0x0000007B (0xFFFFF880009A9928, 0xFFFFFFFFC0000034, 0x0000000000000000, 0x0000000000000000).
The INACCESSABLE_BOOT_DEVICE error in this case is caused by the fact that the hard disk controller of the new server (computer or virtual machine) is different from the original hardware. For example, most hypervisors use a SCSI or SAS controller to connect virtual hard disks by default, which is disabled by default in Windows. The lsi_sas.sys driver is installed, but the service it runs is disabled. As a result, the operating system will not be able to load the necessary controller drivers, and Windows will stop booting with BSOD.
In debug mode, you may notice that Windows boot stops at the CLASSPNP.SYS driver loading stage.
To fix error 0x0000007B, you need to boot from any Windows installation media or bootable disk (for example, MsDaRT). If you booted your computer from install media, you will need to press Shift + F10 On the first screen of the installation wizard (you then select a language and keyboard layout). The command prompt window will appear and you will need to run the command:
Regedit.exe
navigate to HKEY_LOCAL_MACHINE registry hive and select file , load hive in the registry editor window. Choose \Windows\System32\config\SYSTEM File on local server drive (don’t confuse this with WinPE drive). This file stores the system portion of your Windows Registry.
These steps will mount your System Registry hive from your hard drive in Registry Editor. Enter a temporary name for the new registry hive (for example, use the name local_hkey,
go to HKEY_LOCAL_MACHINE\local_hkey\ControlSet001\services\ registry key in the hive that you have mounted.
Find these registry keys:
Find the called REG_DWORD parameter Start and change it 0 (0x0000000000) in each of these keys.
Comment, A value of start = 0 means that this service (and associated drivers) will be loaded on Windows startup. A value of start = 3 means that the service must be started manually.
If you had set your SATA controller mode to AHCI before this error appeared, you should also set Start = 0 in msahci section.
To save the changes to the local registry file on disk, select your registry key HKEY_LOCAL_MACHINE\local_hkey and click remove hive from the menu.
Now you can restart your server. Windows should boot normally. It will automatically search for and install the drivers for your new disc controller.
If after making these changes your Windows still does not boot with the same INACCESSABLE_BOOT_DEVICE error, it means that you are using a different type of disk controller.
Try changing the value of Start parameter in HKEY_LOCAL_MACHINE\local_hkey\ControlSet001\services key as per the table below.
| windows service name | VMware or Hyper-V Virtual Machine | Physical PC running Windows x64 with native SATA adapter | Physical PC with RAID controller |
| Separate | 3 | 3 | 3 |
| amdide | 3 | 3 | 3 |
| But | 0 | 0 | 0 |
| cmdide | 3 | 3 | 3 |
| iastorv | 3 | 3 | 3 |
| Understand | 0 | 3 | 3 |
| Msahci | 3 | 0 | 0 |
| pciide | 3 | 0 | 3 |
| sign post | 3 | 3 | 3 |
| LSI_SAS | 0 | 3 | 3 |
How to manually install driver when INACCESSABLE_BOOT_DEVICE error occurs?
You can manually install the drivers to your offline windows image. For example, after performing a P2V host migration, you can install the VMware SCSI disk controller or the VirtIO driver (for KVM virtualization) in an offline Windows image. To do this, copy the necessary drivers to a bootable USB flash drive, boot from it and open Command Prompt.
To install the driver to an offline Windows image (in this example it’s on the F: drive), run the command
dism /image:f:\ /add-driver /driver:vioscsi.inf
Some organizations have configured Group Policies that restrict the installation of third-party drivers on Windows. For example, with the following options under Computer Configuration -> Administrative Templates -> System -> Device Installation -> Device Installation Restrictions:
- Prevent installation of devices matching any of these device IDs
- Prevent installation of devices using drivers that match these device setup classes
- prevent installation of removable devices
- Prevent installation of tools described by other policy settings.
If these policies are enabled, Windows cannot automatically install the controller driver.
In this case, you will need:
- boot your computer from boot media and
\Windows\System32\config\SYSTEMregistry hive from the local drive (as described above); - Then navigate to the following registry key
HKEY_LOCAL_MACHINE\local_hkey\System\ControlSet001\Control\PnP - change to disable cdb And DontStartRawDevices registry value
0 - Unload the registry hive and restart your computer.
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