BSOD 86 (INSTRUCTION_COHERENCY_EXCEPTION): causes and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: INSTRUCTION_COHERENCY_EXCEPTION

Could be also:
Constant	Type	OS
ERROR_INVALID_PASSWORD	Win32 error	Windows
ESTRPIPE	errno	Linux
EBADARCH	errno	Mac
ELIBMAX	errno	Solaris

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DATA_COHERENCY_EXCEPTION	XNS_INTERNAL_ERROR

INSTRUCTION_COHERENCY_EXCEPTION

INSTRUCTION_COHERENCY_EXCEPTION is bug check 0x56. Microsoft's reference marks the code as very infrequent and does not document portable meanings for the four arguments. The name alone therefore cannot identify a particular instruction-cache operation, CPU defect, or driver routine.

Preserve execution context instead of expanding the name

Coherency behavior is architecture-sensitive, and the public bug-check page does not provide a common syndrome layout. Retain the original dump, processor architecture, Windows build, and platform firmware information. The stack and debugger-visible machine context are the evidence to use when deciding whether a software path, platform issue, or corrupted state is involved.

Recommended evidence

Keep every raw bug-check parameter for same-build comparison.
Use !analyze -show 0x56 for debugger-known metadata and !analyze -v for the actual dump.
Compare instruction context and loaded module versions across repeats before making a hardware conclusion.

References

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