Geeks in Phoenix

Geek Blog


How to check and repair system files in Windows 11

When it comes to repairing Windows-based computers, I always do one thing: check for corrupt system files. Corrupt system files can cause all sorts of problems, so here is how to check and repair system files in Windows 11.

How to check and repair system files in Windows 11

Repairing system files is not complex, but it can be time-consuming. Going through all of the steps outlined in this article can take several hours. Once you start a scan, you will have to allow it to complete, so be prepared to watch your computer work. And all of the links included in this article will open in a new window.

We first need to check the drive's file structure that the operating system is installed on. It is usually drive C:. For this, we will use the disk error checking program built into Windows 11.

There are a couple of different ways to run it (standard and advanced), but the most thorough way is by using the advanced method (see link below). It may take some time to run, but it is the most thorough error checking you can perform.

How to check your drive for errors in Windows 11

Now that we have checked the drive for errors, we must check for corrupted system files. For this, we will use the built-in System File Checker (SFC). Like most of the programs in this article, this program has to be run from an Administrative Command Prompt.

How to open a Command Prompt with Administrator privileges in Windows 11

SFC has multiple syntaxes and parameters you can use with it. Here are all of the syntaxes and parameters with examples of their use.

SFC [/SCANNOW] [/VERIFYONLY] [/SCANFILE=<file>] [/VERIFYFILE=<file>] [/OFFWINDIR=<offline windows directory> /OFFBOOTDIR=<offline boot directory> [/OFFLOGFILE=<log file path>]]

  • /SCANNOW - Scans integrity of all protected system files and repairs files with problems when possible.
  • /VERIFYONLY - Scans integrity of all protected system files. No repair operation is performed.
  • /SCANFILE - Scans integrity of the referenced file, repairs file if problems are identified. Specify full path <file>.
  • /VERIFYFILE - Verifies the integrity of the file with full path <file>. No repair operation is performed.
  • /OFFBOOTDIR - For offline repair, specify the location of the offline boot directory.
  • /OFFWINDIR - For offline repair, specify the location of the offline windows directory.
  • /OFFLOGFILE - For offline repair, optionally enable logging by specifying a log file path.

Examples:

  • SFC /SCANNOW
  • SFC /VERIFYFILE=c:\windows\system32\kernel32.dll
  • SFC /SCANFILE=d:\windows\system32\kernel32.dll /OFFBOOTDIR=d:\ /OFFWINDIR=d:\windows
  • SFC /SCANFILE=d:\windows\system32\kernel32.dll /OFFBOOTDIR=d:\ /OFFWINDIR=d:\windows /OFFLOGFILE=c:\log.txt
  • SFC /VERIFYONLY

System File Checker running in an Administrative Command Prompt inside of Windows 11
We want to check all of the Windows 11 protected system files, so type the following into an Administrative Command Prompt and press Enter.

SFC /SCANNOW

System File Checker results in an Administrative Command Prompt inside of Windows 11
Now four (4) possible results can appear when SFC is done scanning. They are:

Windows Resource Protection did not find any integrity violations.
All system files are acceptable, and you are good to go.

Windows Resource Protection could not perform the requested operation.
There may be another program preventing SFC from running. In this case, boot the system up into safe mode and run SFC from there.

Windows Resource Protection found corrupt files and successfully repaired them.
All system files are now correct, and you're ready to go. Just restart your computer to finalize the repairs. If you want to view the repair details, type the following into an Administrative Command Prompt and press Enter.

findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt"

It will create a text file on your desktop named sfcdetails.txt that has all of the details of the repaired files.

Windows Resource Protection found corrupt files but was unable to fix some of them.
If you received this message, you will need to repair the hidden Windows image. To do this, we will need to run the Deployment Image Servicing and Management (DISM) program.
Deployment Image Servicing and Management running in an Administrative Command Prompt inside of Windows 11
To restore the health of the Windows image, type the following into an Administrative Command Prompt and press Enter.

DISM /Online /Cleanup-image /Restorehealth

Once DISM finishes, run SFC /SCANNOW again. This time no integrity violations should be found. If, after several attemps at automatically repairing the corrupt system file(s) fails, you may have to fix them manually. To view the details of the files that could not be automatically repaired, type the following into an Administrative Command Prompt and press Enter.

findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log >"%userprofile%\Desktop\sfcdetails.txt"

It will create a text file on your desktop named sfcdetails.txt. You will need to search through it and find what file(s) could not be repaired

How to manually repair corrupt system files

Note: To replace a corrupt system file, you must have a known good copy of the file(s) in question. A good file source is another computer or virtual machine running Windows 11. Since I do computer repair for a living, I have all of the versions of Windows that are still supported by Microsoft running inside virtual machines.

The first thing to do is note the location (path) and name of the file(s) that need to be replaced from the sfcdetails.txt file. Once you have another copy of the corrupt file(s), you will need to take administrative ownership of the file(s). To do this, modify the following command with the path\filename of the file you want to replace and then type it into an Administrative Command Prompt and press Enter.

takeown /f path\filename

Example: takeown /f C:\Windows\FileToBeReplaced.dll

Next, you will have to grant administrators full access to the file(s) being replaced. To do this, modify the following command with the path\filename of the file you want to replace and then type it into an Administrative Command Prompt and press Enter.

icacls path\filename /grant administrators:F

Example: icacls C:\Windows\FileToBeReplaced.dll /grant administrators:F

The third thing to do is copy the new file(s) and replace the corrupt one(s).To do this, modify the following command with the path\filename of the file you want to replace and then type it into an Administrative Command Prompt and press Enter.

copy path\filename path\filename

Example: copy C:\Temp\FileToBeReplaced.dll C:\Windows\FileToBeReplaced.dll

Troubleshooting Windows Update problems

Updated July 7, 2020

When it comes to repairing Windows computers, there seems to be a couple of problems that I get a lot of help requests. One of them is when a computer cannot get updates to Windows. So here are a few of my favorite resources for fixing Windows Update.

Troubleshooting Windows Update problems

There are several reasons why Windows Update can fail. There could be corrupted files or folders; the different services that Windows Update requires are not starting, registry errors, etc. The following is a list of some of the procedures I use to repair Windows Update.

Remember to always restart your computer after running any of these procedures before trying Windows Update again.

Windows Update Troubleshooter

This is probably the easiest and most common way to repair Windows Update. Microsoft has a Windows Update Troubleshooter for Windows 7 and Windows 8.1 online. Just follow the link below and then click on Update Troubleshooter for Windows 7 and Windows 8. You can either run the troubleshooter or save the file. I recommend saving it to your hard drive. That way, if you need to rerun it, you will already have it ready to go.

Windows Update Troubleshooter

Windows 10 has several troubleshooters built-in, including one for Windows Update. All of the Troubleshooters are located in Windows Settings. There are a few different ways to get to Windows Settings.

  1. Left-click on the Start Windows logo menu and left-click on Settings (the gear icon)
  2. Right-click on the Start Windows logo menu or press the Windows logo key Windows logo + X and select Settings from the Power User menu
  3. Press the Windows logo key Windows logo + I

Once you have Windows Settings open, select Update and Security, then Troubleshoot in the left-hand column, then select Windows Update in the right-hand column.

So if the Windows Update Troubleshooter (repair) did not fix the issue, you could try resetting all of the Windows Update components. The following link has a PowerShell script for resetting the Windows Update components automatically. It also has instructions on how to reset the Windows Update components manually. I recommend using the PowerShell script unless you are comfortable with going through all the manual procedures. When prompted to run or save the script, I recommend that you save it to your hard drive, just in case you need to rerun it.

Reset Windows Update components

There is another way to reset the Windows Update components. The Reset Windows Update Tool is s script-based application that performs the same functions as the script above. Along with resetting Windows Update components, it can run Secure File Checker (see below), repair invalid registry keys, and repair the Windows system image using DISM (see below).

Reset Windows Update Tool

Check your drive for errors

If you have run both of the Windows Update troubleshooters (repair/reset) and Windows Update is still not functioning correctly, it's time to do some general system checks. Sometimes there can be an error(s) with the file system that does not allow the troubleshooters to fix the issue(s). I have had this problem many times before. Nothing worse than feeling like a dog chasing his tail. At this point, I recommend checking your hard drive for errors by running checkdisk.

Check your hard disk for errors in Windows 7 and Windows Vista

Check your hard drive for errors in Windows 8

Check your hard drive for errors in Windows 10

Once you are done with a checkdisk, go ahead and rerun the Windows Update Troubleshooters. First, run the repair troubleshooter and try checking for updates. If it doesn't fix it, run the reset troubleshooter. If Windows Update still won't work, then it is time to check to system files.

Check system files

SFC

Windows has a built-in program called System File Checker (SFC) to check system files for corruption and incorrect versions. SFC is run inside of an administrative command prompt. Just follow the link below for your version Windows for instructions on how to bring up an admin command prompt.

Open an Administrative Command Prompt in Windows Vista / Windows 7

Open an Administrative Command Prompt in Windows 8 / Windows 8.1

Open an Administrative Command Prompt in Windows 10

SFC is the same in all of the currently supported versions of Windows. Here is the link to the most detailed instructions for SFC (Windows 10).

Check Windows 10 system files with System File Checker

Once you are done running SFC and have corrected any problems it may have found, try running Windows Update. If it still doesn't work, try running the troubleshooters (repair/reset) one at a time, running Windows Update in between. If you again cannot run Windows Update successfully, it may be time to run the most advanced system corruption repair tools.

DISM (Windows 8/8.1, Windows 10) / SUR (Windows Vista, Windows 7)

Deployment Image Servicing and Management (DISM) and System Update Readiness tool (SUR) are the complete way of checking for file corruption in Windows. The link to the instructions on how to run both is below. DISM and SUR are meant to be used by advanced users, so if you don't feel comfortable running either one of these programs, please contact a local computer repair shop like Geeks in Phoenix for assistance.

Fix Windows Update errors by using the DISM or System Update Readiness tool

After running either DISM or SUR, check again to see if Windows Update will work. If Windows Update still does not work, it may be time to reset or reinstall Windows. The instructions on how to do this can be found online. If you require assistance with this process, please contact a local computer repair shop like Geeks in Phoenix.

Free computer diagnostics

Repairing a PC can sometimes be expensive, and that is why we offer free basic in-shop diagnostics. Give one of our professional and experienced technicians a call at (602) 795-1111, and let's see what we can do for you.

Check out our reviews

Geeks In Phoenix LLC, BBB Business Review

Customer service is #1

Here at Geeks in Phoenix, we take pride in providing excellent customer service. We aim to give the highest quality of service  from computer repair, virus removal, and data recovery.

Bring your computer to us and save

Repairing a computer can be time-consuming. That is why we base our in-shop service on the time we work on your computer, not the time it takes for your computer to work! From running memory checking software to scanning for viruses, these are processes that can take some time.

Contact us

If you have any questions, please feel free to give us a call at (602) 795-1111  and talk with one of our Geeks. Or you can send us a message from our contact page contact page , and one of our Geeks will get back to you as soon as possible. Or you can stop by and see us. Here are our hours and location.

Like Geeks in Phoenix on Facebook

Follow Geeks in Phoenix on Twitter

Watch Geeks in Phoenix on YouTube