Windows Boot Loop Diagnostics

You may encounter a situation when you can't boot Windows anymore, but there is no specific error message or error code to search for. Windows just keeps rebooting in a loop, and BSoD (blue screen of death) appears just for a tiny fraction of second, so details about the error can't be read.

There's a special registry value to prevent automatic reboot on BSoD. After changing this registry value with Emergency Boot Kit, you will have enough time to read details about the error (such as error code and error message), and continue your search for the solution.

Contents

1. In a nutshell

A registry value HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl\AutoReboot of type REG_DWORD controls whether Windows would instantly reboot on blue screen of death.

1 means instant automatic reboot, 0 means manual reboot by user intervention (e.g. pressing reset button or power cycling).

This applies to all versions of Windows from Windows XP to Windows 10, as well as equivalent Windows Server operating systems.

2. Step by step guide

1) Download Emergency Boot Kit and deploy it to USB thumbdrive. Set up your BIOS to boot from USB thumbdrive.

2) Run Emergency Boot Kit Registry Editor:

Windows Boot Loop Diagnostics - Starting Emergency Boot Kit Registry Editor
Windows Boot Loop Diagnostics - Starting Emergency Boot Kit Registry Editor

3) Choose Windows installation from the list:

Windows Boot Loop Diagnostics - Choosing Windows Installation
Windows Boot Loop Diagnostics - Choosing Windows Installation

4) Open HKEY_LOCAL_MACHINE\SYSTEM registry hive:

Windows Boot Loop Diagnostics - Opening Registry Hive
Windows Boot Loop Diagnostics - Opening Registry Hive

4) Note the value of Select\Current (NNN). Use arrow keys (UP and DOWN) to navigate registry keys, ENTER key to enter/leave current registry key, TAB key to change active panel:

Windows Boot Loop Diagnostics - Opening Select Registry Key
Windows Boot Loop Diagnostics - Opening Select Registry Key
Windows Boot Loop Diagnostics - View the registry value of HKEY_LOCAL_MACHINE\SYSTEM\Select\Current
Windows Boot Loop Diagnostics - View the registry value of HKEY_LOCAL_MACHINE\SYSTEM\Select\Current

5) Go to registry key ControlSetNNN\Control\CrashControl:

Windows Boot Loop Diagnostics - Open HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001 registry key
Windows Boot Loop Diagnostics - Open HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001 registry key
Windows Boot Loop Diagnostics - Open HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control registry key
Windows Boot Loop Diagnostics - Open HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control registry key
Windows Boot Loop Diagnostics - Open HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\CrashControl registry key
Windows Boot Loop Diagnostics - Open HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\CrashControl registry key

6) Set value AutoReboot to 0. Regions shown in black are editable.

Windows Boot Loop Diagnostics - View the registry value of HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\CrashControl\AutoReboot
Windows Boot Loop Diagnostics - View the registry value of HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\CrashControl\AutoReboot
Windows Boot Loop Diagnostics - Disable automatic reboot on BSoD
Windows Boot Loop Diagnostics - Disable automatic reboot on BSoD

7) Press F2 to save changed registry hive HKEY_LOCAL_MACHINE\SYSTEM to disk, then press F10 to exit the Registry Editor.

Windows Boot Loop Diagnostics - Saving Registry Hive
Windows Boot Loop Diagnostics - Saving Registry Hive

8) Finally, choose Reboot in the main menu of Emergency Boot Kit.

Windows Boot Loop Diagnostics - Rebooting Emergency Boot Kit
Windows Boot Loop Diagnostics - Rebooting Emergency Boot Kit