Windows BSOD APC_INDEX_MISMATCH — What It Means & How to Fix It

Fix Windows Blue Screen of Death APC_INDEX_MISMATCH (0x00000001) caused by mismatched APC state in a kernel thread. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: APC_INDEX_MISMATCH (bug check 0x00000001) occurs when a kernel thread's APC disable count is mismatched on entry/exit. APC (Asynchronous Procedure Call) tracking ensures kernel operations are properly synchronized. This BSOD is commonly triggered by audio drivers, display drivers, or SATA/AHCI controllers. The crash dump will identify the specific driver that caused the APC mismatch. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Realtek or other audio drivers with bugs in their kernel-mode components. Display drivers (NVIDIA, AMD, Intel) performing incorrect kernel operations. Storage controller drivers entering or leaving critical regions incorrectly. Windows Update installing a driver version incompatible with the current kernel. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Analyze the crash dump: open C:\Windows\Minidump\*.dmp with WinDbg and run !analyze -v to identify the driver. Update the identified driver from the manufacturer's website (not Windows Update). If the audio driver is at fault, uninstall Realtek drivers and let Windows install a generic driver. Roll back the driver: Device Manager > right-click device > Properties > Driver tab > Roll Back Driver. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Windows Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.