macOS kernel return 50 (KERN_CODESIGN_ERROR): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: A page fault was rejected because code-signature validation rejected the requested page.

Could be also:
Constant	Type	OS
ERROR_NOT_SUPPORTED	Win32 error	Windows
ippStsUnknownFeature	Intel Ipp Status	Any
ENOCSI	errno	Linux
ENETDOWN	errno	Mac
EBADE	errno	Solaris
PHASE1_INITIALIZATION_FAILED	BugCheck Code	Windows

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KERN_OPERATION_TIMED_OUT	KERN_POLICY_STATIC

KERN_CODESIGN_ERROR

A page-fault result from code-signing validation

KERN_CODESIGN_ERROR has a specific XNU meaning: during a page fault, the requested page was rejected by a signature check. This is not equivalent to an unmapped address, a normal protection failure, or a transient backing-store error.

The investigation must preserve both the virtual-memory context and the code-signing evidence. A later launch or loader message can be secondary; the page-fault result identifies the point where the kernel refused to supply the page after signature validation.

What to inspect

Collect the executable or mapped code resource, architecture, and macOS build context.
Keep code-signing, notarization, trust, and loader diagnostics emitted before the fault.
Check whether the file was modified, replaced, truncated, or sourced from an unexpected deployment path.
Distinguish this result from KERN_MEMORY_ERROR, where a backing memory object could not return data without a signature rejection.

References

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