Windows 7 / Getting Started

How to Restore the Last Known Good Configuration

Last Known Good Configuration is usually used to enable the operating system to start if it fails after the Starting Windows logo is displayed. Using Last Known Good Configuration helps to correct instability or startup problems by reversing the most recent system, driver, and registry changes within a hardware profile. When you use this feature, you lose all configuration changes that were made since you last successfully started your computer.

Using the Last Known Good Configuration restores previous drivers and also restores registry settings for the subkey HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet. Windows Vista does not update the LastKnownGood control set until you successfully start the operating system in normal mode and log on.

When you are troubleshooting, it is recommended that you use Last Known Good Configuration before you try other startup options, such as safe mode. However, if you decide to use safe mode first, logging on to the computer in safe mode does not update the LastKnownGood control set. Therefore, Last Known Good Configuration remains an option if you cannot resolve your problem by using safe mode.

To access the Last Known Good Configuration startup option, follow these steps:

  1. Remove all floppy disks, CDs, DVDs, and other bootable media from your computer and then restart your computer.
  2. Press F8 at the operating system menu. If the operating system menu does not appear, press F8 repeatedly after the firmware POST process completes but before the Starting Windows logo appears. The Advanced Boot Options menu appears.
  3. On the Advanced Boot Options menu, select Last Known Good Configuration (Advanced).

Use Last Known Good Configuration to restore some settings to their state during the last time a user successfully logged on.

When Windows starts, it reads status information from the file %WinDir%\Bootstat.dat. If Windows detects that the last startup attempt was unsuccessful, it automatically displays the startup recovery menu, which provides startup options similar to the Advanced Boot Options menu, without requiring you to press F8.

Note If you suspect that changes made since you last successfully restarted the computer are causing problems, do not start Windows and log on normally-logging on overwrites the LastKnownGood control set. Instead, restart the computer and use the Last Known Good Configuration. You can also log on in safe mode without overwriting the Last Known Good Configuration. For more information about control sets, see the section titled "Kernel Loading Phase" earlier in this tutorial.

How to Use System Restore

If Last Known Good Configuration fails to resolve the problem, you can manually perform a system restore if Startup Repair did not initiate it. However, Startup Repair would typically have taken this step already if it might have solved the problem. For information on how to use System Restore, see the section titled "How to Use System Restore" earlier in this tutorial.

[Previous] [Contents] [Next]

In this tutorial:

  1. Configuring Startup and Troubleshooting Startup Issues
  2. What is New with Windows Startup
  3. Boot Configuration Data
  4. BCD Stores
  5. System Recovery
  6. Windows Boot Performance Diagnostics
  7. Understanding the Startup Process
  8. Power-on Self Test Phase
  9. Initial Startup Phase
  10. Initial Startup Phase for BIOS Computers
  11. Initial Startup Phase for EFI Computers
  12. Windows Boot Manager Phase
  13. Windows Boot Loader Phase
  14. Kernel Loading Phase
  15. Control Sets
  16. Values for the Start Registry Entry
  17. Value Descriptions for Type Entries
  18. Other Registry Entries in the Servicename Subkeys
  19. Session Manager
  20. Logon Phase
  21. Important Startup Files
  22. How to Configure Startup Settings
  23. How to Use the Startup And Recovery Dialog Box
  24. How to Use the System Configuration Tool
  25. How to Use BCDEdit
  26. How to Interpret BCDEdit Output
  27. How to Back Up and Restore Settings
  28. How to Change the Default Operating System Entry
  29. How to Change the Boot Menu Time-Out
  30. How to Change the Order of Boot Manager Menu Items
  31. How to Create an Entry for Another Operating System
  32. How to Remove a Boot Entry
  33. How to View and Update Global Debugger Settings
  34. How to Remove the Windows 7 Boot Loader
  35. How to Configure a User Account to Automatically Log On
  36. How to Disable the Windows Startup Sound
  37. How to Speed Up the Startup Process
  38. The Process of Troubleshooting Startup
  39. Startup Troubleshooting Before the Starting Windows Logo Appears
  40. How to Start the System Recovery Tools
  41. How to Run Startup Repair
  42. How to Use BootRec.exe
  43. How to Diagnose Hardware Problems
  44. How to Use System Restore
  45. How to Manually Repair the Boot Sector
  46. How to Manually Update the BCD Registry File
  47. How to Manually Replace Files
  48. How to Reinstall Windows
  49. Startup Troubleshooting After the Starting Windows Logo Appears
  50. How to Restore the Last Known Good Configuration
  51. How to Enable Boot Logging
  52. How to Start in Safe Mode
  53. How to Identify Failing Drivers and Services
  54. How to Analyze Startup Problems in Safe Mode
  55. Event Viewer (Eventvwr.msc)
  56. System Information
  57. Error Reporting Service
  58. How to Use Device Manager to View or Change Resources
  59. How to Analyze Boot Logs
  60. How to Roll Back Drivers
  61. How to Temporarily Disable a Service
  62. Troubleshooting Startup Problems After Logon
  63. How to Temporarily Disable Startup Applications and Processes
  64. How to Disable Startup Applications Using the Shift Key
  65. How to Disable Startup Programs Using the System Configuration Utility
  66. How to Disable Startup Applications Configured Using Group Policy or Logon Scripts
  67. How to Permanently Disable Startup Applications and Processes
  68. Manually Remove the Entry