APC_INDEX_MISMATCH error

The APC_INDEX_MISMATCH error Blue Screen of Death (BSOD) occurs in Windows 11 and Windows 10 due to mismatched asynchronous procedure calls (APCs). APCs are a mechanism used by the Windows operating system to manage high-priority tasks efficiently. When a process incorrectly manages these calls, it leads to system instability, triggering this error. The primary causes of this error include incompatible drivers, corrupted system files, faulty hardware, and outdated Windows updates. Whatever the reason, if you’re encountering this error, this article explores how to troubleshoot and fix APC_INDEX_MISMATCH error.

How to Fix APC_INDEX_MISMATCH Error

Windows Blue Screen of Death (BSOD) usually occurs due to driver conflicts, software bugs, or hardware-related failures. The APC_INDEX_MISMATCH error occurs when the system detects an inconsistency in the way asynchronous procedure calls (APCs) are being handled.

  • Incompatible or Outdated Drivers – Some device drivers may be outdated, incompatible, or incorrectly installed, leading to system instability.
  • Corrupt or Missing System Files – Essential system files required for Windows operations might be missing or damaged.
  • Faulty Hardware (RAM, SSD, or GPU Issues) – Defective RAM modules, storage drives, or graphics cards may trigger this BSOD error.
  • Recent Windows Updates or Software Conflicts – A newly installed update or third-party software might conflict with system processes.
  • Overclocking or Power Management Issues – Improper overclocking settings or power configuration might cause instability.

Remove External Devices and Restart Your PC

External devices such as USB drives, printers, or external hard disks may cause conflicts and cause this blue screen error. Let’s first disconnect all peripherals and restart your PC to check if the error gets fixed. If the error stops occurring, reconnect the devices one by one to identify the problematic one.
If your PC continues to restart frequently due to this error, boot into Safe Mode to perform the following solutions and fix the BSOD error.

Windows 10 Safe mode

Update or Reinstall Drivers

As discussed, this BSOD error mostly occurs due to a corrupted or outdated driver issue. So first, find out and try to update or reinstall problematic drivers, especially the Display graphic Driver, Audio sound and Network adapter driver.
Steps to update drivers:

  • Press Win + X and select Device Manager.
  • Expand the category related to the faulty driver (e.g., Display Adapters, Sound Controllers).
  • Right-click on the driver and select Update driver > Search automatically for drivers.
  • Restart your PC after updating the driver.

Update display driver
If updating doesn’t work, reinstall the driver:

  • Right-click the device and select Uninstall device.
  • Restart your PC; Windows will reinstall the driver automatically.
  • If the issue persists, download the latest driver manually from the manufacturer’s website.

Check and Repair Corrupted System Files

Also, corrupted system files cause Different Startup Errors, including the APC_INDEX_MISMATCH error. Windows has built-in tools like System File Checker (SFC) and Deployment Image Servicing and Management (DISM) to scan and repair these files.

  • Open Command Prompt as Administrator (Win + X > Command Prompt (Admin) or PowerShell (Admin)).
  • Then, type sfc /scannow and hit the enter key. This will start scanning for missing, damaged or corrupted system files.
  • If found, the SFC utility will restore them from a compressed folder located on %WinDir%\System32\dllcache.
  • Wait until the scanning process is 100% complete. After that, restart Windows and check if there are no more startup BSOD errors.

system file checker utility Windows 10

Also, if SFC utility Results windows resource protection found corrupt files but was unable to fix some of them, then run the DISM Restore health command which Repairs the System image and enables sfc to do its job.

DISM /Online /Cleanup-Image /RestoreHealth

Uninstall Recently Installed Programs or Updates

If the error started after installing a new program or update, it might be causing conflicts. Sometimes, incompatible software changes system settings, leading to errors.

If you notice the problem started after a recent Windows update:

  • Open Settings using (Win + I).
  • Go to Update & Security > Windows Update > Update history.
  • Click Uninstall updates.
  • Select the most recent update and click Uninstall.
  • Restart your PC and check if the error is resolved.


Steps to remove recent programs if the problem started after install new software or App.

  • Open Control Panel > Programs & Features.
  • Find the recently installed software.
  • Right-click and select Uninstall.
  • Restart your PC and check if this helps fix the blue screen error.

Disable Overclocking and Reset BIOS Settings

Overclocking can push hardware beyond its intended limits, causing instability and errors like APC_INDEX_MISMATCH.

  • Restart your PC and enter BIOS/UEFI (usually by pressing F2, F12, DEL, or ESC during boot).
  • Look for Overclocking settings and disable them.
  • Select Load Default Settings or Reset to Factory Defaults.
  • Save changes and exit BIOS.
  • Restart your PC and check if the error persists.

Check for Hard Drive Corruption

Sometimes Disk Drive Errors, bad Sectors, Faulty HDD cause Different Startup Errors and Windows failed to start with different BSOD errors. Run the Disk Check Utility CHKDSK to fix disk errors that may cause this apc index mismatch Blue Screen error.

  • To check and fix disk Drive errors, open the command prompt as administrator,
  • Then, type the command chkdsk c: /f /r  and hit the enter key.

Run Check disk on Windows 10

Here command CHKDSK is the short of Check Disk, C: is the drive letter you want to check, /F means fix disk errors and /R stands for recover information from bad sectors.

When it prompts, “Would you like to schedule this volume to be checked the next time the system restarts? Press Y and restart your computer. This will scan and repair the disk drive errors wait 100% complete after that Windows start normally.

Check Faulty RAM and run the Memory Diagnostic Tool

Also, sometimes the Faulty memory module (RAM) causes different Blue Screen errors. If all the above methods failed to fix APC_INDEX_MISMATCH BSOD error then check your RAM. simply remove your computer’s RAM, clean it, and reinsert it perfectly after few seconds. You have to make sure that you unplug all the power cords.

Also, Run The memory Diagnostic Tool to check and Fix Memory Errors.

  • Press Win + R, type mdsched.exe, and press Enter.
  • Select Restart now and check for problems.
  • Your PC will restart and run a memory test. If issues are found, consider replacing your RAM.

Disable Fast Startup Feature

Some users report disable Fast Startup feature helps them to fix most startup problems, including this Blue Screen error.

  • Open the Control panel, Search for and select power options
  • Choose What the power buttons do. Click on Change Settings, which are currently unavailable.
  • Then, under Shutdown Settings, Uncheck the option Turn on Fast Startup (Recommended) and click Save Changes.

Fast Startup

Make Sure Your System Is Updated

Microsoft regularly drops Updates with new features, security improvements, and bug fixes to patch the holes created by third-party applications. May these bug fixes help to resolve the apc index mismatch error, So make sure your Windows computer is updated and have the latest updates installed.

Recently, Microsoft has released Windows 10 KB5001567 with bug fixes for blue screen error APC_INDEX_MISMATCH.

Addresses an issue that might cause a blue screen when attempting to print to certain printers using some apps and might generate the error, APC_INDEX_MISMATCH. Microsoft support site

  • Press Win + I to open Settings.
  • Navigate to Windows Update.
  • Click Check for updates and install any pending updates.
  • Restart your PC after installation.

Windows update

Make Sure your computer is not infected with any virus or malware infection, which may cause Different Startup errors, including Blue Screen errors. We recommend installing a good antivirus / antimalware application with the latest updates and performing a full system scan.

Also, install a free system optimizer like CCleaner to clean junk, cache, System error, memory dump files etc and fix broken or missing registry Errors.

Also read:

Steve Ballmer
Steve Ballmer
With over 7 years of experience in the IT industry, I have experience in IT support, helpdesk, sysadmin, network admin, and cloud computing. Certified in Microsoft Technologies (MCTS and MCSA) and also Cisco Certified Professional in Routing and Switching.

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