I've just downloaded the Xcode 27.0 beta 5 on a macOS 26.6.1 machine and tried to build my app (which includes Metal CoreImage kernels). I'm met with a new (to me) error;
/Users/…/Developer/…/air-lld:1:1 symbol(s) not found for target 'air64_v28-apple-macosx26.0.0'
and from the build log;
air-lld: warning: ignoring file '/Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreImage.framework/Versions/A/CoreImage.metallib', file AIR version (2.9) is bigger than the one of the target being linked (2.8)
air-lld: error: symbol(s) not found for target 'air64_v28-apple-macosx26.0.0'
metal: error: air-lld command failed with exit code 1 (use -v to see invocation)
I have no MTL_LANGUAGE_REVISION in my build settings.
If I add one, with value Metal41 the app builds fine, but crashes at runtime as Metal 4.1 isn't supported on macOS 26.
I imagine this is a beta Xcode and or macOS SDK bug, is there a workaround?