Error: Debugging Isn't Possible Because a Kernel Debugger is Enabled on the System


When you debug managed code, you might receive the following error message:

Debugging isn't possible because a kernel debugger is enabled on the system  

This message occurs when you try to debug managed code:

  • on a Windows 7 or Windows Vistasystem that has been started in debug mode.

  • the application uses the CLR version CLR 2.0, 3.0, or 3.5.

To fix this problem

  • Upgrade your application to use CLR version 4.0 or 4.5


  • Disable kernel debugging and debug in Visual Studio.


  • Debug using the Kernel Debugger instead of Visual Studio.


  • In the Kernel Debugger, disable user-mode exceptions.

To disable kernel debugging in the current session

  • At the command prompt, type:

    Kdbgctrl.exe -d  

To disable kernel debugging for all sessions (Windows Vista and Windows 7)

  1. At the command prompt, type:

    bcdedit /debug off   
  2. Restart the computer.

To disable kernel debugging for all sessions (other Windows operating systems)

  1. Locate boot.ini on your system drive (usually C:\). The boot.ini file might be hidden and read-only. Therefore, you must use the following command to see it:

    dir /ASH  
  2. Open boot.ini using Notepad and remove the following options:

  3. Restart the computer.

To debug with the Kernel Debugger

  1. If the Kernel Debugger is hooked up, you will see a message that asks whether you want to continue to debug. Click the button to continue.

  2. You might get a User break exception(Int 3). If this occurs, type the following Kernel Debugger command to continue to debug:


Debugger Security
Debugging Managed Code