How to Fix Unknown Hard Error in Windows 10

The “Unknown Hard” error that keeps on appearing in Windows 10 can put users in an unpleasant situation. This kind of error leads to the freezing of the taskbar, blackening of the screen, and sudden disappearance of the icons on the Desktop. And each time you try to open Windows, the system will only give you an error message saying that it’s a critical error and some applications like Start and Cortana won’t work.

Upon analysis, it seems that the “sihost.exe” is not responding and that it is the one that’s causing the c000021a Unknown Hard error to pop up. Sihost.exe files represent the Shell Infrastructure Host which is an essential component in the Windows operating system. The Windows Shell Infrastructure Host is primarily responsible for handling some graphical elements of the operating system interface such as the Start menu and the taskbar transparency. And so if the Shell Infrastructure or Sihost.exe has stopped, has been removed, or corrupted, you will most likely have issues with the overall functionality of the Windows operating system and you’ll get the Unknown Hard error

In addition, the ctfmom.exe Unknown Hard error may also occur due to incompatible drivers installed on your PC. Ctfmom is a process that identifies inputs such as handwriting, languages, and many more. It’s the one that controls the functions of background behavior. To resolve this issue, you need to first try to identify which application is the one that’s running the sihost.exe file. And if needed, you need to either update or reinstall or completely uninstall the problematic application.

Option 1 – Try to run the System File Checker

The SFC Scan or System File Checker, us a built-in utility in Microsoft Windows that can be found in the C:\Windows\System32 folder. This tool allows users to scan and restore any corrupted system files in Windows that might be causing the Unknown Hard error to appear. Before you use this tool, make sure to find out whether the sihost.exe on your computer is a Trojan that you have to remove or if it’s a file that belongs to a trusted Windows application. Once you have that sorted out, follow the steps below.

  • Tap Win + R to launch Run.
  • Type in cmd in the field and tap Enter.
  • After opening Command Prompt, type in sfc /scannow

The command will start a system scan which will take a few whiles before it finishes. Once it’s done, you could get the following results:

  1. Windows Resource Protection did not find any integrity violations.
  2. Windows Resource Protection found corrupt files and successfully repaired them.
  3. Windows Resource Protection found corrupt files but was unable to fix some of them.

Option 2 – Try to use System Restore

You can also try using System Restore. This is one of the ways you can use it to back up your PC. Since restore points are created automatically each week by System Restore, you can use System Restore to restore your computer back to an earlier good point in time.

Option 3 – Try to troubleshoot the error in a Clean Boot State

Putting your PC in a Clean Boot state can help you diagnose and troubleshoot the issues in your system. During this state, you can start the system with a minimum number of drivers and startup programs that will surely help you in isolating the root cause of the Unknown Hard Error.

  • Log onto your PC as an administrator.
  • Type in MSConfig in the Start Search to open the System Configuration utility.
  • From there, go to the General tab and click “Selective startup”.
  • Clear the “Load Startup items” checkbox and make sure that the “Load System Services” and “Use Original boot configuration” options are checked.
  • Next, click the Services tab and select the “Hide All Microsoft Services” checkbox.
  • Click Disable all.
  • Click on Apply/OK and restart your PC. (This will put your PC into a Clean Boot State. And configure Windows to use the usual startup, just simply undo the changes.)

After putting your PC in a Clean Boot State, try creating a system restore point and see if the problem still occurs. Clean Boot troubleshooting is designed to help you isolate the problem. For you to execute a clean boot troubleshooting, you must do a couple of actions (the steps are given above) and then restart your PC after every action. You might have to disable one third-party app after the other to really isolate the issue. And once you’ve narrowed down the problem, you can either disable the third-party app that’s causing the problem or remove it. Note that you must switch your PC back into the Normal Startup mode after you’re done troubleshooting the problem. Here’s how you can do it:

  • From the “Start” menu, go to System Configuration.
  • After that, switch to the General tab and click the option for “Normal Startup”.
  • Next, go to the Services tab and clear the checkbox for “Hide all Microsoft services”.
  • Then find and click “Enable all” and if prompted, you have to confirm.
  • Afterward, go to the Task Manager and enable all the Startup programs and confirm the action.
  • Restart your PC when prompted.

Congratulations, you have just fixed the Unknown Hard error in Windows 10 all by yourself. If you would like to read more helpful articles and tips about various software and hardware visit errortools.com daily.

Now that’s how you fix the Unknown Hard error in Windows 10 on a computer. On the other hand, if your computer is going through some system-related issues that have to get fixed, there is a one-click solution known as Restoro you could check out to resolve them. This program is a useful tool that could repair corrupted registries and optimize your PC’s overall performance. Aside from that, it also cleans out your computer for any junk or corrupted files that help you eliminate any unwanted files from your system. This is basically a solution that’s within your grasp with just a click. It’s easy to use as it is user-friendly. For a complete set of instructions in downloading and using it, refer to the steps below

Perform a full system scan using Restoro. To do so, follow the instructions below.

      1. Download and install Restoro from the official site.
      2. Once the installation process is completed, run Restoro to perform a full system scan.
        restoro application screen
      3. After the scan is completed click the “Start Repair” button.
        restoro application screen
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