Fixing ‘Unable to Access Default Device–Set’ in Xcode

When attempting to create a new simulator in Xcode, I encountered the following error:

Unable to access default device–set

This issue has been discussed in the Apple Developer Forums (thread 1, thread 2), but no definitive solution was provided.

Troubleshooting Attempts

Here are the steps I tried, none of which resolved the issue:

  • Restarting the Mac.
  • Reinstalling Xcode.
  • Changing the xcode-select path:
    sudo xcode-select -s ~/Downloads/Xcode.app/
  • Manually installing the Simulator runtime (guide).

Root Cause and Solution

The issue was related to permissions. Running the following commands without sudo failed:

xcrun simctl list devices
xcodebuild -importPlatform ~/Downloads/iOS_18.2_Simulator_Runtime.dmg

The error logs indicated a problem with the ~/Library/Developer/CoreSimulator/Devices directory:

Error Domain=com.apple.CoreSimulator.SimError Code=400 "Unable to determine SimDeviceSet for subscriptions, set_path=~/Library/Developer/CoreSimulator/Devices"

I found a similar bug reported on Stackoverflow. He indicated that the issue was due to the missing ~/Library/Developer/CoreSimulator/Devices directory.

Upon investigation, I found that the Developer directory was owned by root, causing permission issues:

mkdir ~/Library/Developer/CoreSimulator

# -> Permission denied

To fix this, I changed the ownership of the Developer directory as same as ~/Library directory:

drwx------@ 101 paul  staff  3232  7 Feb 08:01 Library

sudo chown -R paul:staff ~/Library/Developer

After this, I successfully imported the simulator runtime:

xcodebuild -importPlatform ~/Downloads/iOS_18.2_Simulator_Runtime.dmg

importing ~/Downloads/iOS_18.2_Simulator_Runtime.dmg
Registered as 9A66D486-5FAE-436A-B0E3-DC2AA9F9****.

Now, I can create new simulators in Xcode without any issues. Navigate to Xcode -> Window -> Devices and Simulators -> + to add a new simulator.

Cheers!