With Xcode 26.0.1, specifying both -buildVersion 26.0 and -architectureVariant arm64 works.

This issue still occurs in Xcode 26 Release Candidate.

-buildVersion is still broken in Xcode 26 beta 5. Also in beta 5 if you do not specify -architectureVariant arm64, the iOS simulator fails to download.

I found that if you download it from the command line and add -architectureVariant arm64 to the command that it downloads okay.

I also tried: ⏺ ~ > xcodebuild -downloadPlatform iOS -buildVersion 26.0 -architectureVariant arm64 Finding content... iOS 26.0 (arm64Only) is not available for download.

Any update on this? The "buildVersion" parameter is still broken in Xcode 26 beta 4.