There's a regression in Xcode 26.x (26.0 ... 26.5 beta) where xcodebuild is not able to download platforms when it is behind proxy. $ env | grep PROXY HTTP_PROXY=..... HTTPS_PROXY=..... $ xcodebuild -version Xcode 26.5 Build version 17F5012f $ xcodebuild -downloadPlatform iOS -buildVersion 23E244 -exportPath ./test Finding content... iOS 23E244 is not available for download. Xcode 26.x GUI is able to download from behind proxy though. The last known Xcode which used to be able to download platforms from behind a proxy was Xcode 16.4. $ xcodebuild -version Xcode 16.4 Build version 16F6 $ xcodebuild -downloadPlatform iOS -buildVersion 23E244 -exportPath ./test Downloading iOS 26.4 Simulator (23E244): 0.0% (66 kB of 10.6 GB) The relevant feedback ID: FB22125784

On freshly set Mac, or in VM, when there is NO internet access, xcrun simctl boot <UDID> fails to boot any simulator with the error: Unable to boot device because we cannot determine the runtime bundle xcrun simctl list devices displays all created simulators with error message: runtime profile not found using "System" match policy As soon as you connect machine/VM to the internet, and start Xcode.app GUI, everything starts to work. Internet can be disconnected afterwards. This is very bad for CI automation. Feedback filled https://feedbackassistant.apple.com/feedback/13098070