Hello Developers and Apple Engineers,
I am encountering a persistent and highly unusual Xcode build failure when trying to use Metal APIs, specifically related to MTLCommandQueueDescriptor. I have exhausted all standard troubleshooting steps, including a complete erase and reinstall of macOS, yet the issue remains. Hardware diagnostics have passed. I am seeking insights or potential solutions.
The Problem:
When compiling any project (including brand new, empty macOS App projects) that attempts to set the dispatchType property on an MTLCommandQueueDescriptor instance, the build fails with the following errors:
Swift
// Code causing the error: let queueDescriptor = MTLCommandQueueDescriptor() queueDescriptor.dispatchType = .userInteractive // <-- Error occurs here
// Compiler Errors: Value of type 'MTLCommandQueueDescriptor' has no member 'dispatchType' Cannot infer contextual base in reference to member 'userInteractive' Key Evidence - Physical Header File Corruption:
The root cause appears to be a physically corrupted/incomplete SDK header file. Using the cat command in Terminal to inspect the contents of the relevant Metal header file confirms that the definition for MTLCommandQueueDescriptor is missing the dispatchType property:
Bash
cat /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/Metal.framework/Versions/A/Headers/MTLCommandQueue.h The output consistently shows MTLCommandQueueDescriptor only having maxCommandBufferCount and logState properties, even after a fresh OS and Xcode installation.
Environment:
macOS: Version 26.0.1 (Build 25A362) - Clean install via Erase and Reinstall from Recovery.
Xcode: Version 26.0.1 (Build 17A400) - Installed fresh from Mac App Store after OS reinstall.
Mac Hardware: MacBook Pro (14-inch, M3) - (Please confirm this model info is accurate)
Hardware Diagnostics: Passed (Tested at an official Apple Store).
Exhaustive Troubleshooting Steps Performed (Issue Persists After All):
Standard Xcode Cleaning:
Clean Build Folder (Shift+Cmd+K).
Manually deleted DerivedData folder (~/Library/Developer/Xcode/DerivedData).
Deleted Xcode Caches (~/Library/Caches/com.apple.dt.Xcode, com.apple.dt.xcodebuild).
Command Line Tools Path:
Correctly set using sudo xcode-select -s /Applications/Xcode.app/Contents/Developer.
Verified path using xcode-select -p.
Verified version using xcodebuild -version.
Multiple Xcode Versions & Install Methods Attempted (Before OS Reinstall):
Xcode 26.0.1 (App Store).
Xcode 26.0.1 (.xip package from Developer Portal).
Xcode 26.1 Beta 3 (.xip package from Developer Portal).
Performed thorough cleaning (deleted ~/Library/Developer, /Library/Developer, caches, rebooted) before each .xip installation attempt.
In all cases, cat command confirmed the header file remained corrupted on disk after installation.
Hardware Check:
Took the Mac to an official Apple Store. Hardware diagnostics passed without any issues reported.
Complete OS Reinstallation:
Booted into Recovery Mode.
Used Disk Utility to completely erase the internal SSD (APFS, GUID Partition Map).
Reinstalled macOS 26.0.1 from Recovery.
Set up the Mac as a new device (did not restore from backup).
Post-OS Reinstall:
Installed Xcode 26.0.1 fresh from the Mac App Store.
Set command line tools path correctly.
Created a brand new macOS App project (MetalTest).
Pasted the minimal code to reproduce the issue into AppDelegate.swift.
Build failed with the exact same errors.
Ran the cat command again, confirmed the MTLCommandQueue.h file on the fresh system is STILL missing the dispatchType property.
Request for Help:
Given that the SDK header file corruption persists even after a complete macOS erase and reinstall, and hardware diagnostics have passed, I am at a loss for the cause or further troubleshooting steps.
Has anyone encountered a similar situation where core SDK files remain corrupted despite a clean OS install and passing hardware checks?
Are there any deeper system caches or states that might survive an erase/reinstall and interfere with SDK file integrity?
Are there any more advanced diagnostic steps recommended?
Any insights or suggestions from Apple engineers or the community would be greatly appreciated.
Thank you.
I have previously contacted Apple Developer Support regarding this issue, case ID: 102731239935.