What does BSOD 127 (UNEXPECTED_KERNEL_MODE_TRAP) mean?

UNEXPECTED_KERNEL_MODE_TRAP

UNEXPECTED_KERNEL_MODE_TRAP meaning

UNEXPECTED_KERNEL_MODE_TRAP is bug check 0x0000007F. The processor generated a trap that the kernel could not handle. Parameter 1 is the trap number; a double fault, commonly trap 8, often points to kernel stack exhaustion or a second fault during exception handling.

How to analyze UNEXPECTED_KERNEL_MODE_TRAP

Decode the trap number, inspect the trap frame and stack, and look for recursive filter-driver paths, stack overrun, CPU or memory faults, overclocking, and mismatched hardware. Multiple dumps help distinguish a stable software stack from random hardware corruption.

• Preserve the complete dump, all four parameters, Windows build, loaded modules, and the event timeline before changing drivers or firmware while investigating UNEXPECTED_KERNEL_MODE_TRAP.
• Run !analyze -v and follow the parameter-specific objects and the stack associated with UNEXPECTED_KERNEL_MODE_TRAP rather than relying only on the symbolic name or a single probable-cause line.
• Compare multiple dumps when available; a stable instruction or object path associated with UNEXPECTED_KERNEL_MODE_TRAP is stronger evidence than a module that appears only after earlier corruption.

Recovery boundary for UNEXPECTED_KERNEL_MODE_TRAP

Correct the driver recursion, stack use, firmware, or hardware condition shown by the trap. Do not assume all 0x7F crashes are memory failures; the trap number and repeated stack pattern are decisive.

Official references for UNEXPECTED_KERNEL_MODE_TRAP

• Microsoft: UNEXPECTED_KERNEL_MODE_TRAP bug check
• Microsoft: Bug check code reference
• Microsoft: Analyze a kernel-mode dump with WinDbg

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