Causes and Solutions for the “APC Index Mismatch” Blue Screen Error – 2025

Causes and Solutions for the “APC Index Mismatch” Blue Screen Error

The “APC Index Mismatch” blue screen error is one of the many BSOD (Blue Screen of Death) errors in Windows. It’s frustrating, sudden, and can happen even when you’re in the middle of important work. This error usually appears with a code such as 0x00000001 and leads to a system crash, forcing your computer to restart. But what does it mean, and how can you fix it?

This guide will explain the causes behind the APC Index Mismatch error and walk you through several solutions to fix it effectively.

What Is the APC Index Mismatch Error?

The “APC Index Mismatch” BSOD refers to a mismatch in the Asynchronous Procedure Call (APC) state index. In simpler terms, it means that a kernel-mode process or driver tried to perform an operation without properly managing asynchronous calls, leading to system instability.

This mismatch often results from driver issues, especially audio or video drivers, or from incompatible third-party software.

Common Causes of the APC Index Mismatch Error

There isn’t a single universal cause for this issue. However, some of the most common triggers include:

• Faulty or outdated device drivers

• Corrupted system files

• Incompatible software (e.g., antivirus programs)

• Improper hardware configurations

• Fast startup or hibernation bugs

• Third-party software that interacts with Windows kernel

Fix 1: Update or Reinstall Device Drivers

Drivers are one of the leading causes of this BSOD error. Outdated or corrupted drivers, especially for audio (Realtek), graphics, or Logitech webcam drivers, are known to cause this issue.

Steps to Update Drivers:

1. Press Windows + X and select Device Manager.

2. Locate the suspected driver, such as Sound, video and game controllers or Display adapters.

3. Right-click the device and choose Update driver.

4. Select Search automatically for drivers.

If this doesn’t help, uninstall the driver and reinstall the latest version manually from the manufacturer’s website.

Fix 2: Run Windows Memory Diagnostic

Faulty RAM can sometimes cause this error.

Steps:

1. Press Windows + R, type mdsched.exe, and press Enter.

2. Choose Restart now and check for problems.

3. Let the tool run — your computer will restart and check the memory.

If it detects issues, consider replacing your RAM.

Fix 3: Disable Fast Startup

Fast Startup can sometimes cause conflicts during boot, especially if there are driver mismatches.

Steps to Disable Fast Startup:

1. Go to Control Panel > Power Options.

2. Click on Choose what the power buttons do.

3. Select Change settings that are currently unavailable.

4. Uncheck Turn on fast startup (recommended).

5. Click Save changes and restart your computer.

Fix 4: Uninstall Problematic Third-Party Software

Some third-party software, especially antivirus programs, has been reported to interfere with system-level operations, leading to this BSOD.

Recommended:

• Temporarily uninstall your antivirus software (such as Norton or Avast) to see if the error disappears.

• Restart your computer and observe its behavior.

You can always reinstall the antivirus later, preferably with a version that’s known to be stable with your version of Windows.

Fix 5: Run System File Checker and DISM

Corrupt system files may also lead to the APC Index Mismatch error.

Steps:

1. Press Windows + X and open Command Prompt (Admin) or Windows Terminal (Admin).

2. Type the following commands, one at a time:

Wait for it to complete, then run:

After both commands finish, restart your computer.

Fix 6: Update Windows

Microsoft frequently releases updates that patch known bugs and improve hardware compatibility.

Steps:

1. Open Settings > Update & Security > Windows Update.

2. Click Check for updates.

3. Download and install all available updates, then restart your system.

Fix 7: Check for Recently Installed Hardware or Software

If the error started after installing a new device or application, that might be the cause.

What You Can Do:

• Uninstall any recently added hardware or software.

• Reboot your computer.

• Check if the blue screen reappears.

Fix 8: Boot Into Safe Mode

Safe Mode loads Windows with a minimal set of drivers and services, which can help determine if third-party drivers or services are causing the issue.

Steps:

1. Press Windows + R, type msconfig, and press Enter.

2. Go to the Boot tab and check Safe boot.

3. Choose Minimal and click OK.

4. Restart your computer.

If the error does not occur in Safe Mode, the problem likely lies with a third-party driver or service.

Fix 9: Perform a Clean Boot

A clean boot helps identify software conflicts by loading only essential Windows services.

Steps:

1. Open System Configuration (msconfig).

2. On the Services tab, check Hide all Microsoft services.

3. Click Disable all.

4. Go to the Startup tab and click Open Task Manager.

5. Disable all startup items.

6. Restart your PC.

Gradually re-enable services to identify the culprit.

Fix 10: Replace or Remove Problematic Hardware

If you’ve recently installed new RAM, a graphics card, or peripherals, and none of the software fixes have worked, try the following:

• Disconnect or replace the suspected hardware.

• Reboot the PC.

• See if the BSOD reoccurs.

Defective or incompatible hardware can trigger this error at the system level.

Conclusion

The “APC Index Mismatch” blue screen error might seem intimidating at first, but in most cases, it’s related to driver incompatibility or system file corruption. By methodically updating drivers, disabling problematic software, or adjusting system settings like Fast Startup, you can usually resolve the issue without needing professional help.

If none of the above solutions work, you may need to consider a clean Windows installation as a last resort — but in most cases, one of these steps will do the trick.