0x1: APC_INDEX_MISMATCH – Windows Error

Error Details : The APC_INDEX_MISMATCH bug check has a value of 0x00000001. This indicates that there has been a mismatch in the APC state index.



The following parameters are displayed on the blue screen.

Parameter Description
1 The address of the system function (system call) or worker routine.
2 The value of the current thread’s ApcStateIndex field.
3 The value of current thread’s CombinedApcDisable field. This field consists of two separate 16-bit fields: (Thread->SpecialApcDisable << 16) | Thread->KernelApcDisable.
4 Call type (0 – system call, 1 – worker routine).



The most common cause of this bug check is when a file system or driver has a mismatched sequence of calls to disable and re-enable APCs. The key data item is the Thread->CombinedApcDisable field. The CombinedApcDisable field consists of two separate 16-bit fields: SpecialApcDisable and KernelApcDisable. A negative value of either field indicates that a driver has disabled special or normal APCs (respectively) without re-enabling them. A positive value indicates that a driver has enabled special or normal APCs too many times.

Possible Resolutions

This is a kernel internal error. This error occurs on exit from a system call. A possible cause for this bug check is when a file system or driver has a mismatched sequence of system calls to enter or leave guarded or critical regions. For example, each call to KeEnterCriticalRegion must have a matching call to KeLeaveCriticalRegion. If you are developing a driver, you can use Static Driver Verifier, a static analysis tool available in the Windows Driver Kit, to detect problems in your code before you ship your driver. Run Static Driver Verifier with the CriticalRegions rule to verify that your source code uses these system calls in correct sequence.

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