“APC Index Mismatch” Blue Screen Error Cause and How To Fix It

Learn how to fix the APC Index Mismatch blue screen error on a Windows 10 operating system. Here are several ways you can try to troubleshoot.

The BSoD (blue screen of death) is one of the most dreaded errors in Windows, and it can happen for any number of reasons. One such BSoD error that has been appearing lately with increasing frequency is APC Index Mismatch, which shows up as the APC_INDEX_MISMATCH code once the error occurs.

“APC Index Mismatch” Blue Screen Error Cause and How To Fix It

This blue screen error causes your computer to crash seemingly out of nowhere, and you're left without access to anything on your device. You might lose some of your work, and there may be a deeper issue in your system that repeats the error over and over again.

The good news? You can do a few simple things to fix this issue and prevent it from happening again in the future!

Table of Contents 

What is an APC Index Mismatch?

Asynchronous Procedure Call (APC) is an abbreviation for a function that operates outside of the main program when specific conditions are met. Many blue screen errors default to pointing towards an APC Index Mismatch when something goes wrong on your computer, that is why there are so many different causes for this error.

The APC Index Mismatch error usually indicates that there is an inconsistency with the number of processes that entered and exited an area of operations where a program is operating. As a result, your system experiences a BSOD crash. This is effectively the operating system warning you that it’s unable to run software without risk of damaging the machine.

If you’re currently struggling with the APC Index Mismatch BSOD crashes, the following fixes might help. Below are some methods other users in a similar situation have used to resolve the issue. Please follow each method until you encounter one that works for your particular problem.

How to fix APC Index Mismatch on Windows 10

Method 1. Examine your RAM

A hardware malfunction can cause the APC Index Mismatch error, even if you don’t suspect it. If you overclock your CPU, GPU, or RAM frequencies and experience the BSOD crash, revert back to the default frequencies and see if this fixes system stability.

If your problem is solved, the issue may have been caused by too much overclocking. Try to slowly increase the frequencies again, but no more than a few percent at a time.

examine your RAM

Note that if you’re not sure if your system is overclocked, it likely isn't, and this may be a problem with one or more pieces in your computer's internal components. You can try replacing your RAM, CPU or GPU. But don't jump the gun! There’s also a possibility that it’s a simple software error, like a faulty driver or some corrupt system files.

Before purchasing a new computer component, try the following methods to see if you’re able to resolve the APC Index Mismatch error on a software level.

Method 2. Update to the latest release of Windows 10

An update to your operating system may fix a lot of underlying issues, such as the primary cause of the APC Index Mismatch blue screen error. Try to download the latest version of Windows 10 to see if the crash still persists afterward.

  1. Click on the Windows icon in the bottom left of your screen to bring up the Start menu. Choose Settings, or alternatively use the Windows + I shortcut.
    update windows
  2. Click on the Update & Security tile. This is where you can find most of your Windows Update settings and choose when to receive updates.
    update windows
  3. Make sure to stay on the default Windows Update tab. Click on the Check for updates option and wait for Windows 10 to find available updates. If you see any updates already displayed, click on the View all optional updates link to see and install them.
    windows update
  4. If an update is found, click on the Install option and wait for Windows 10 to download and apply the necessary updates.

Method 3. Install the latest Realtek High Definition driver

A common cause for the APC Index Mismatch blue screen error is outdated or corrupted audio drivers, especially for Realtek components. You can easily fix it by downloading and installing the latest compatible drivers for your system. Click here to be navigated to the Realtek download page, where you can download the latest drivers.

Once the file downloads, click on it to launch the driver installer. You need to restart your computer after a successful driver installation. When the device boots up, see if you’re able to use it without experiencing another APC Index Mismatch crash.

Method 4. Disable the Realtek HD Audio Manager from startup

Try to disable the Realtek Audio Manager from starting on your computer. Users have reported that this method helps if the problem has something to do with a webcam or Skype. Even if you don’t have either of these components, try disabling this software and see if it improves your PC’s condition.

  1. Right-click on an empty space in your taskbar and choose Task Manager. If the Task Manager launched in compact mode, make sure to expand details by clicking on the “Mode details” button.
    disable the realtek HD Audio Manager
  2. witch to the Start-up tab using the header menu located at the top of the window. Here, find the Realtek HD Audio Manager from the list and select it by clicking on it once.
  3. Click on the Disable button now visible in the bottom-right of the window. This will disable the application from launching when you start your device.
    update  audio drivers
  4. Restart your computer.

Method 5. Repair corrupted system files

Corrupted systems files can cause massive problems with your operating system. You can identify and repair faulty system files through the SFC scan and the DISM tool.

The System File Checker (SFC) is a built-in tool to help troubleshooting in Windows 10. It's able to automatically detect corrupted system files, and repair them to working order. You can use the SFC scan to potentially fix a variety of errors.

The DISM tool also allows you to identify and fix corruption issues with your system by simply running commands in the Command Prompt application. It checks for corruption system-wide, and automatically attempts to restore damaged or missing files.

  1. Open the search bar in your taskbar by clicking on the magnifying glass icon. You can also bring it up with the Windows + S keyboard shortcut.
  2. Type Command Prompt in the search box. When you see it in the results, right-click on it and choose Run as Administrator.
    command prompt
  3. When prompted by the User Account Control (UAC), click Yes to allow the app to launch with administrative permissions.
  4. Type in the following command and press Enter to execute it: sfc /scannow
    sfc/ scannow
  5. Wait for the System File Checker to finish scanning your computer. If any discrepancy is detected, the utility will restore the necessary system files and attempt to fix all errors related to them.
  6. Next, start the DISM scan. Type in the following command and press Enter to execute it: DISM.exe /Online /Cleanup-image /Scanhealth
    DISM scan health
  7. Next, you need to execute a command to fix any issues found on your system. Simply type in the following line and press Enter again: DISM.exe /Online /Cleanup-image /Restorehealth
    DISM scan health
  8. Wait for the process to finish. Upon completion, close the Command Prompt window and restart your device. 

The SFC scan and DISM tool may take some time to run through your system and identify any missing or corrupted system files. Even if the scans fail to find anything, some users have reported that their PC's functionality improved after running the commands above.

Method 6. Uninstall the DisplayLink driver

If you use DisplayLink software, it may be the source for the APC Index Mismatch problem on your device. Many users sent reports that some drivers are not compatible with the Windows 10 system, and removing them solved the constant system crashes.

  1. Press the Windows + R keys on your keyboard. This is going to bring up the Run utility.
  2. Type in “appwiz.cpl” without the quotation marks and press the Enter key on your keyboard. This will launch the Control Panel application and take you straight to the Programs and Features page.
    uninstall dispay link driver
  3. Scroll down in your list of installed programs and locate the DisplayLink Core application. Right-click on it once, and select Uninstall from the context menu.
    uninstall display link driver
  4. After uninstalling the software, click here to download the DisplayLink Installation Cleaner. Run the application once to remove all remains of the DisplayLink driver and potentially fix your blue screen error.

Method 7. Use the Blue Screen troubleshooter

Windows 10 comes with a variety of troubleshooters that aim to automatically solve issues on your computer. This makes solutions more accessible to users. Users have found that the Blue Screen troubleshooter is able to address and fix errors related to the APC_INDEX_MISMATCH error code.

While the troubleshooter may not be able to restore the files and progress you lost due to the system crash error, it may help prevent another one.

  1. Click on the Windows icon in the bottom left of your screen to bring up the Start menu. Choose Settings, or alternatively use the Windows + I shortcut.
  2. Click on the Update & Security tile. This is where you can find most of your built-in troubleshooter.
    blue screen troubleshooter
  3. Switch to the Troubleshoot tab using the left-side pane. Here, you should be able to see a troubleshooter titled Blue Screen.
    blue schreen troubbleshooter
  4. If you don’t share full diagnostic data to Microsoft, click on the Additional troubleshooters link and locate the Blue Screen troubleshooter there.
    bluescreen troubleshooter
  5. Click on the Run the troubleshooter button. Wait for the troubleshooter to scan your device and identify any issues.

As always, this troubleshooter is not perfect. It may or may not detect any issues with your system but that doesn't mean our other methods can't repair the error you're getting on screen.

Method 8. Disable virtualization in your BIOS

Many Windows 10 users have reported the APC Index Mismatch BSOD error while using some Trend Micro tools on their computers. This is likely because of an issue with the Virtualization feature in your computer, which often interferes with tools leading to this problem appears.

If you don’t require virtualization on your computer, you can easily turn it off in the BIOS without having to sacrifice any of your programs.

Just follow these steps.

  1. Click on the Windows icon in the bottom-left of your screen to bring up the Start menu.
  2. Click on the Power option, and then choose Restart. This is going to close all of your open applications and completely restart your computer.
    dsiable virtualization in BIOS
  3. As your computer is booting, press the F2 key on your keyboard. This is the general function key needed to enter the BIOS, but some computers and laptops may have a different key assigned. You can try holding F8, F10, F12, or Del.
    disable virtualization in Bios
  4. When the BIOS screen shows up, use the arrow keys to navigate and find the Virtualization feature. If you can’t find it, use a search engine to get help, or contact the manufacturer’s support!
  5. When you locate the Virtualization feature, disable it. Once it’s been disabled, restart your computer and check if the problem is solved or not.

Keep in mind that the Virtualization feature may be in a different location depending on your BIOS version and brand. If your BIOS doesn't have Virtualization or you’ve already disabled it before, skip to the next solution.

Method 9. Reset or reinstall Windows 10

If nothing above worked, your issue may only be fixed if you reset or reinstall Windows 10. Depending on your preferences, you may reinstall the system without losing any personal files. Unfortunately, most of your applications and system configuration will be deleted in order to give your device a fresh start.

Check our How to Install Windows 10, 8.1 or 7 Using a Bootable USB guide for detailed, step-by-step instructions on how to install Windows 10. For refresh and reset instructions, head to the official Microsoft support page.

Final thoughts

If you find yourself on the Blue Screen of Death or experiencing any other issue with your computer, don't worry! You're probably only one step away from fixing it - we have all those fixes for you in our article. Plus, there are more articles about Windows 10 on our blog if you want to learn even more about this awesome OS!

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