How to fix APC_INDEX_MISMATCH BSoD error in Windows 11/10

What is APC_INDEX_MISMATCH error

APC_INDEX_MISMATCH error is a Blue Screen of Death (BSoD) that can occur in Windows 11 or 10 systems when the operating system detects a mismatch in the asynchronous procedure call (APC) state index. This problem typically arises due to faulty drivers, incompatible hardware, or software conflicts, and frequently points to issues with system-level drivers like graphics or audio components. It is commonly associated with the file “win32k.sys”, indicating that a kernel-mode driver has attempted to perform an illegal operation. Users may experience this error after installing new hardware, updating Windows, or even during routine use of applications such as Microsoft Office or video conferencing tools like Zoom. The error is frustrating because it causes your system to crash, often without warning. It may also be triggered by third-party antivirus software or corrupted system files. In some cases, incorrect memory configurations or BIOS settings can also play a role. When this BSoD appears, your system collects error data and restarts, which can result in data loss if not properly handled. It is essential to resolve this issue quickly to avoid recurring crashes and potential hardware damage. Fortunately, there are several methods to diagnose and fix the root cause of this error. This guide will walk you through each solution step-by-step to help you restore system stability.

Step-by-step instructions to fix APC_INDEX_MISMATCH error

1. Update Device Drivers

1. Press Windows + X and select Device Manager.
2. Expand device categories (such as Display adapters or Sound, video and game controllers).
3. Right-click each device and select Update driver.
4. Select Search automatically for drivers and follow the prompts.

Updating each driver manually is time- and energy-consuming. If you are willing to save it and update drivers faster, we recommend using a special utility called Driver Booster from IObit. It has broad databases of drivers for all of the devices you need to maintain your PC. You can download it using the button below.

Driver Booster start screen

Driver Booster scan results

Driver Booster tools section

2. Run SFC and DISM Scans

1. Press Windows + S, type cmd, right-click Command Prompt, and choose Run as administrator.
2. Type sfc /scannow and press Enter.
3. Wait for the scan to complete and follow any on-screen instructions.
4. After SFC, run these DISM commands one at a time:
   • DISM /Online /Cleanup-Image /CheckHealth
   • DISM /Online /Cleanup-Image /ScanHealth
   • DISM /Online /Cleanup-Image /RestoreHealth

Windows 11 Start -> Terminal (Admin)

Windows 11 Terminal -> sfc /scannow

3. Uninstall Conflicting Applications

1. Press Windows + I to open Settings.
2. Go to Apps > Installed apps.
3. Identify recently installed or potentially conflicting software (like third-party antivirus or audio/video editing tools).
4. Click the three-dot menu next to the app and select Uninstall.

4. Check for Windows Updates

1. Press Windows + I to open Settings.
2. Navigate to Windows Update.
3. Click Check for updates and install any available updates.

Windows 11 -> Settings

Settings ->Windows Update

Windows Update -> Check for Updates

5. Disable Realtek HD Audio Manager from Startup

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Go to the Startup tab.
3. Look for Realtek HD Audio Manager.
4. Right-click and choose Disable.
5. Restart your computer to check if the issue is resolved.

6. Perform a Clean Boot

1. Press Windows + R, type msconfig, and press Enter.
2. Under the Services tab, check Hide all Microsoft services and click Disable all.
3. Switch to the Startup tab and click Open Task Manager.
4. Disable all startup items and close Task Manager.
5. Click OK in the System Configuration window and restart your PC.

7. Update or Roll Back Graphics Drivers

1. Open Device Manager as shown earlier.
2. Expand Display adapters and right-click your graphics driver.
3. Select Update driver or choose Properties > Driver tab > Roll Back Driver if the issue started after an update.

Updating each driver manually is time- and energy-consuming. If you are willing to save it and update drivers faster, we recommend using a special utility called Driver Booster from IObit. It has broad databases of drivers for all of the devices you need to maintain your PC. You can download it using the button below.

Driver Booster start screen

Driver Booster scan results

Driver Booster tools section

8. Check RAM for Errors

1. Press Windows + R, type mdsched.exe, and press Enter.
2. Choose Restart now and check for problems.
3. Let Windows Memory Diagnostic complete and review the results after reboot.

9. Restore System to a Previous Point

1. Press Windows + S, type Restore, and select Create a restore point.
2. Click System Restore button.
3. Select a restore point prior to when the error started appearing.
4. Follow the on-screen instructions to restore your system.

10. Perform a System Reset

1. Open Settings using Windows + I.
2. Go to System > Recovery.
3. Click Reset this PC and choose either Keep my files or Remove everything.
4. Follow the prompts to reinstall Windows.