Windows 8 and its successor, Windows 8.1 have more automatic diagnostics built-in than any previous version of Windows to inspect booting related issues and automatically repair them. Startup repair often kicks in by itself when Windows fails to boot. Besides, there are features like Reset and Refresh which significantly make it easier to restore the system to a healthy state by automating the whole procedure. But sometimes, these features are an overkill.
Suppose you installed a bad device driver inadvertently (e.g. some third-party driver to flash your phone) or some software driver and it started causing a BSOD while booting. Or maybe you installed an incorrect version of a particular driver which is not fully compatible. If a Blue screen error starts happening right after you did something like that, then you definitely know what broke your PC and would want to fix it quickly without restoring your whole system using System Restore, let alone Reset/Refresh. While the newly introduced features are useful for automating the restoration of the entire system, they can also take lots of time.
In previous versions of Windows, there was an extremely useful feature called Last Known Good Configuration which allowed you to quickly fix a broken registry hardware configuration to the one when Windows last booted properly. It was very handy in the situation I’ve described above. Last Known Good Configuration stored a copy of the HKEY_LOCAL_MACHINESYSTEMCurrentControlSet key which contains information about all Windows services and drivers.
Selecting Last Known Good Configuration at startup from F8 options did 2 things:
– It restored the hardware configuration in the registry control set indicated by the LastKnownGood key instead of the default
– It restored the device drivers too of the last working configuration, should a newly installed device driver make Windows unbootable
In favor of new additions, this wonderful feature was disabled in Windows 8.1 and Windows 8. The exciting news is that you can still enable it! Let’s see how it can be done.
Create a new DWORD value at the above key called BackupCount by right clicking in the right pane and choosing New -> DWORD value (32-bit) and set its value to 1 or 2, depending on the number of backups you wish to store in the registry. I recommend a value of 2. If the BackupCount value already exists, then simply double click it and set its value to 2.
Now you must create a sub-key. Right click on the ‘Configuration Manager’ key in the left pane and select New -> Key called LastKnownGood. Then create a new DWORD value in the right pane called Enabled and set it to 1 (0 means disabled, 1 means enabled).
Now the Last Known Good Configuration feature is enabled and will start backing up your HKEY_LOCAL_MACHINESYSTEMCurrentControlSet registry branch at every successful boot.
How to access the Last Known Good Configuration in Windows 8.1
To access the Last Known Good Configuration in Windows 8.1, run the following command at an elevated command prompt: