Troubleshooting · Xcode 27.1 beta

iPhone Duo simulator not showing? 7 fixes

You installed the beta, but there's no iPhone Duo in the device list. Work through these in order — fix #1 alone solves most cases.

Fix 1 — You're on the wrong beta

The Duo simulator ships only in the Xcode 27.1 beta. The 27.2 beta does not include it — Apple explicitly points Duo developers at 27.1. Check yours:

xcodebuild -version
# Must say "Xcode 27.1" with a beta build number

Fix 2 — The iOS 27.1 runtime isn't downloaded

The Duo device type requires the iOS 27.1 simulator runtime, which downloads separately and won't appear until it's installed:

xcodebuild -downloadPlatform iOS
# Then verify:
xcrun simctl list devicetypes | grep -i duo
# Expect: com.apple.CoreSimulator.SimDeviceType.iPhone-Duo

Fix 3 — The device was never created

Downloading the runtime doesn't auto-create the device. Open Window → Devices and Simulators, click +, and add an iPhone Duo paired with the iOS 27.1 runtime. Or from the terminal:

xcrun simctl create "iPhone Duo" \
  com.apple.CoreSimulator.SimDeviceType.iPhone-Duo \
  com.apple.CoreSimulator.SimRuntime.iOS-27-1

Fix 4 — Command line tools point at the wrong Xcode

If you have multiple Xcodes installed, the terminal may be talking to the wrong one:

xcode-select -p
# Should point at your 27.1 beta, e.g.:
# /Applications/Xcode-27.1-beta.app/Contents/Developer
sudo xcode-select -s /Applications/Xcode-27.1-beta.app/Contents/Developer

Fix 5 — The simulator service is stuck

CoreSimulator sometimes caches a stale device list. Kill it and let it relaunch:

killall -9 com.apple.CoreSimulator.CoreSimulatorService
# Then reopen Xcode — the service restarts on demand

Fix 6 — Not enough disk space

Simulator runtimes are several GB each, and the 27.1 beta + iOS 27.1 runtime together want ~15 GB free. If the download silently fails, check Settings → General → Storage and clear old runtimes you no longer need:

xcrun simctl list runtimes
xcrun simctl delete unavailable

Fix 7 — Check the basics

Apple Silicon required. The Duo simulator does not run on Intel Macs.
Restart Xcode after installing a runtime — the device list only refreshes on launch.
macOS version. Betas this new usually require a recent macOS; check the 27.1 beta release notes.

Still stuck?

Start over cleanly with the step-by-step install guide, then confirm the device specs match what you see in Device Hub.