Sihost.exe, Ctfmon.exe or Explorer.exe Unknown Hard Error

Published by Nyau Wai Hoe - Updated on

This article addresses an issue wherein users encounter error messages related to Sihost.exe, Ctfmon.exe, or Explorer.exe, particularly upon logging into Windows 11 or Windows 10, often following a Windows Update. The error may also be linked to other process files, depending on your PC’s situation. These error messages may appear randomly while running an app or game.

Another common occurrence of this error is during a Windows rollback loop or the “Choose your language layout” blue screen. After bypassing the loop by creating an admin account username and password to log in to Windows, you may see a Sihost.exe unknown hard error message. After clicking OK or closing the error window, Windows 10 may boot into a black screen with only a working mouse cursor.

Ctfmon.exe unknown hard error or Explorer.exe unknown hard error could indicate the presence of corrupted or missing system files in the OS or conflicts between third-party software and the Windows system.

Sihost.exe Unknown Hard Error Windows 11/10

Clean boot Windows 11 or 10

First, we need to ensure that the problem is not caused by third-party software. To verify this, perform a clean boot on the Windows 10 or 11 PC to prevent other services or programs from loading during startup. If you see a Sihost.exe unknown hard error, try this clean boot method first. Here’s how to clean boot your Windows 10 or 11:

  1. Regardless of whether you’re experiencing a black screen, you can press Win + R to open Run.
  2. Type “msconfig” into the run field and then press Enter.
  3. Go to the General tab.
  4. Select the Selective Startup radio button.
  5. Uncheck the Load startup items option.Selective startup MSConfig
  6. Go to Services tab.
  7. At the bottom, uncheck Hide all Microsoft services.
  8. Then, click on the Disable all button. Ensure you click this only after hiding all Microsoft services.Clean boot explorer.exe unknown hard error
  9. Click Apply, then OK.
  10. Select Restart now.

erify if the problem is resolved. If your Windows 10 or 11 works fine now, re-enable the services one by one from MSconfig to identify the software causing the error.

Run system file check

Errors related to Sihost.exe and Explorer.exe unknown hard error are typically associated with system files. We will perform a system file check to automatically locate and repair any corrupted or missing system files in Windows 10 or 11. Here’s how:

  1. Press Win + X to access the power user menu.
  2. Select Command Prompt (Admin) to open it with administrator privileges.Command prompt
  3. In the command prompt, enter the following command and press Enter.
    sfc /scannow

sfc scannow fix sihost.exe

The scan and repair process will begin upon entering the command. It may take some time. Once completed, restart your PC and check if the problem persists.

Utilize Chkdsk to detect and resolve disk errors

To ensure the issue is not due to a hard disk error, run the ChkDsk command. This is especially common for Sihost.exe and Ctfmon.exe unknown hard error. To run ChkDsk, follow these steps:

  1. Press Win + X to open the Quick Access menu.
  2. Select “Windows Terminal (Admin)” to launch the command prompt with administrative privileges.
  3. In the command prompt, input the following command, and then press Enter:
    chkdsk /f /r

Chkdsk to fix Ctfmon.exe Unknown Hard Error

If the command returns a message stating that ChkDsk cannot run because the volume is in use by another process, type the Y key to schedule the volume check for the next reboot. Restart your computer to allow chkdsk to run.

Roll back to a previous build, restore, or reset Windows 11

If none of the solutions mentioned above work for you, consider rolling back your Windows 11/10 update to a previous build, performing a system restore, or resetting your Windows 11/10 installation. We provide comprehensive guides for all these actions on our website. If you need any assistance, use the search bar at the top of our site to find the relevant information.

Categories: Troubleshoot

Nyau Wai Hoe
Nyau Wai Hoe is the Founder and Chief Editor of With a degree in software engineering and over 12 years of experience in the tech support industry, Nyau has established himself as an expert in the field, with a primary focus on the Microsoft Windows operating system. As a tech enthusiast, he loves exploring new technologies and leveraging them to solve real-life problems.

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