How to Fix APC_INDEX_MISMATCH Error In Windows 10

By | February 27, 2022

Learn how to resolve the APC_INDEX_MISMATCH error when your computer crashes.

APC_INDEX_MISMATCH error is a BSOD error in Windows 10 that can prevent your computer from booting at all. While the error is not very common, you can fix it using some simple troubleshooting methods.

Check Your Computer Drivers

Most Windows 10 blue screen errors, including the APC_INDEX_MISMATCH error, are caused by malfunctioning or outdated drivers. To find out why, look for the filename on the error screen and simply Google it to find the associated driver.

For example, if the crash lists “RtlUpd64.exe” as the reason for the error, the Realtek HD Audio Driver is not working. In this case, you will need to update or uninstall the driver and see if that fixes the error.

How to Update Drivers Using Device Manager

  • Press the button Windows + R to open the Run application. Type devmgmt.msc in the text box and press Enter to open Device Manager.
  • In the Device Manager window, scroll down and expand the section Sound, video and game controllers.
  • Right click on Realtek High Definition Audio (SST) and select Update drivers.
  • At the update prompt, click Search automatically for drivers.
  • Windows will automatically download the latest drivers and install them.

How to Uninstall a Driver

  • Press the button Windows + R to open the Run application. Type devmgmt.msc in the text box and press Enter to open Device Manager.
  • Now, scroll down and expand the section related to the driver you want to remove.
  • Right click on the driver and select Uninstall device.
  • At the uninstall prompt, make sure to check the option Delete the driver software for this device.
  • Click Uninstall and once the process is complete, reboot your computer.

Boot Your Computer Into Safe Mode

Another major reason for the APC_INDEX_MISMATCH error is that third-party applications can interfere with the functioning of your computer.

The best way to diagnose this problem is to check if you are still getting the error after disabling third-party apps. This can be done by cleaning your computer boot or booting it in safe mode.

While clean boot is not an official option in Windows, Safe Mode is, and contains a minimum set of functions and programs.

How to Boot into Safe Mode

  • Click button Start and open Settings.
  • On the Settings dashboard, click Updates & Security.
  • On the navigation bar on the left, click Recovery.
  • Scroll down and below Advanced startup, click Restart now.
  • Your computer will boot to the screen Choose an option.
  • Here, select Troubleshoot > Advanced options > Startup settings > Restart.
  • After your computer reboots, you will see a list of options. On this screen, press F4.
  • Your computer will reboot into Safe Mode.

Now, try to use your computer as usual and see if the APC_INDEX_MISMATCH error persists. If not, it’s likely a third party driver or software is causing the error.

Uninstall recently installed apps or download another version.

Update Windows to Latest Version

Microsoft regularly releases new updates for Windows, and these updates also come with bug fixes. That’s why you should always update your PC to the latest version.

APC_INDEX_MISMATCH error may occur frequently if you are running an old version of Windows which has many unresolved bugs. Luckily, Windows automatically updates itself, but just to be sure, you can manually check for the latest updates.

How to Check for Windows Update

  • Click button Start and click Settings.
  • On the Settings dashboard, click Updates & Security.
  • On the navigation bar on the left, click Windows Update.
  • Click Check for updates.
  • Windows will check the web for the latest updates.
  • If there is an update available, click Download and install.
  • Windows will automatically install the update.

On the other hand, newer updates may cause some unexpected errors, such as the APC_INDEX_MISMATCH error. Although rare, there have been several updates in the past that caused similar errors.

The best way to determine this is to check if the error appears after updating your computer. If it does, it’s likely a new update is causing it. In this case, it is best to uninstall the latest update and wait for another stable update.

How to Delete the Latest Updates

  • Click Start and go to Settings.
  • In the Settings menu, select Updates & Security.
  • Click Windows Update in the navigation bar.
  • Click View update history, and in the next window, click Uninstall updates.
  • Your PC will remove all recently installed Windows updates.

Reset Your Computer (Reset)

This method should be used as a last resort as it will erase all your personal settings, files and apps. If none of the methods mentioned above work, the only solution is to reset your PC or use System Restore if you have created a restore point.

How to Reset Your PC

  • Click on button Start and go to Settings.
  • On the Settings dashboard, click Updates & Security.
  • On the navigation bar, click Recovery.
  • Under Reset this PC here, click Get Started.

In the Reset wizard, you can choose to save your files and applications. This option will simply reinstall Windows but is less likely to work due to a possible other app or file causing the error.

You can also choose to completely wipe your PC and reinstall Windows.

Instead of using Reset this PC, you can also choose to use Windows System Restore to restore your computer to a previous state. But this will only work if you have enabled System Restore previously and Windows has created a restore point.

For a more detailed view of Windows Reset and System Restore, see how to factory reset Windows or use System Restore.

How to Restore Windows to a Previous State

  • In the Start menu search bar, type Recovery.
  • From the search results, click Recovery Control Panel settings.
  • In the next window, click Open System Restore. You will need administrator rights to do this.
  • If you have created a System Restore point, the wizard will ask you to select a restore point.
  • Click Finish.

Resolved APC_INDEX_MISMATCH Error

Using the steps mentioned above, you can resolve the APC_INDEX_MISMATCH BSOD. In addition, these steps can also be used to overcome other common blue screen errors because mostly caused by similar problems.

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