What does macOS kernel return 0xDC00801D (kOSKextReturnKCLoadFailureSystemKC) mean?

 
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kOSKextReturnKCLoadFailure kOSKextReturnKCLoadFailureAuxKC

kOSKextReturnKCLoadFailureSystemKC

The System KC subcode

kOSKextReturnKCLoadFailureSystemKC identifies failure to load the System Kernel Collection. XNU documents it as a subcode of kOSKextReturnKCLoadFailure that can be ORed with the AuxKC subcode. If both System KC and AuxKC fail, the reported low code is 0x1f.

That encoding is useful when decoding a raw integer from logs: the status does not just say “kext problem”; it identifies which collection layer failed. Do not drop the numeric value when normalizing diagnostic events.

How to decode related values

Low code in libkern_kext_errMeaning
0x1cBase Kernel Collection failure family.
0x1dSystem KC failure.
0x1eAuxKC failure.
0x1fBoth System KC and AuxKC failure bits.

Diagnostic priorities

  • Keep the raw status, boot context, and earlier collection diagnostics together.
  • Separate the System KC result from third-party kext approval or AuxKC inclusion evidence.
  • Do not assume a file copied to disk was present in the active collection during the failing boot.

References


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