NTSTATUS 0xC000001D (STATUS_ILLEGAL

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: The processor could not decode or execute the instruction at the current address.

Previous	Next
STATUS_INVALID_SYSTEM_SERVICE	STATUS_INVALID_LOCK_SEQUENCE

STATUS_ILLEGAL_INSTRUCTION

Execution reached an unsupported or invalid instruction encoding

This exception can mean that the byte sequence is not a valid instruction for the active architecture or that it requires a processor feature unavailable on the machine. It can also be a secondary effect of control-flow corruption: a damaged return address or function pointer may branch into data, the middle of another instruction, or an unloaded code region.

Begin with the exact bytes and module mapping at the instruction pointer. If the instruction is valid on newer CPUs, compare deployment feature checks with the compiler target and dispatch logic. If the bytes do not match the on-disk image, investigate patching, memory corruption, or self-modifying/JIT code before replacing the executable.

What to inspect

Disassemble from a known instruction boundary and preserve the raw bytes.
Confirm that the address belongs to committed executable memory and the expected module.
Check CPU feature detection for AVX, AVX-512, or other optional instruction sets.
Compare in-memory code with symbols and the deployed binary before reinstalling anything.

References

Looking for a different code? Search another status or error code.