I'm experiencing a reproducible issue that completely blocks Xcode on an Apple Silicon Mac.
Environment
• MacBook Air (M4) • macOS 26.5.2 (25F84) • Xcode 26.6 (17F113) • Also reproduced with Xcode 26.5 (17F42)
Issue
Xcode terminates immediately before the main window appears.
Instruments also terminates immediately.
The command:
xcodebuild -version
works normally.
However, any command that requires SDK initialization immediately terminates, for example:
xcodebuild -showsdks
The process is killed instantly.
Crash reports consistently show:
SIGKILL (Code Signature Invalid) Termination Reason: Namespace CODESIGNING, Code 2, Invalid Page
The crash occurs during dyld page authentication:
dyld4::fixupPageAuth64()
What I have already tried
• Reinstalled Xcode • Reinstalled macOS • Reinstalled Command Line Tools • Reinstalled Rosetta • Tested in Safe Mode • Tested with a newly created macOS user • Removed caches and DerivedData • Verified Xcode signatures
The behavior is identical in every case.
Interestingly, xcodebuild -version succeeds, but every SDK-related command is killed immediately, suggesting the failure occurs during SDK/framework initialization rather than Xcode startup itself.
I have already submitted:
Feedback Assistant: FB23586800
DTS Case: 20879405
Has anyone else seen the same issue on Apple Silicon (especially M4)?
Any known workaround or confirmation that this may be a macOS 26.5.x / Xcode 26.5–26.6 regression would be greatly appreciated.