The reply by @saeedtkhapple@gmail.com seem to work perfectly. Just want to elaborate further. Ensure you are running Xcode-beta. If you cannot find it on the App store ensure to download it from https://developer.apple.com/download/all/?q=xcode%20beta If you are downloading and installing a new xcode-beta manually after downloading it, do this: 1b. Before installing it, delete the Developer folder in the path /Library/Developer. (Don't worry, it will automatically regenerate the folder when you install a new Xcode. 1c. Uninstall any previous Xcode and restart computer. 1d. Clear trash bin 1e. Install The new Xcode-beta you just downloaded, and move it to the application folder. After installing Xcode-beta, check if you can now download the iOS 18 simulator from the newly installed Xcode-beta. If you still have the error, then you have to manually download and install the simulator. To manually install the simulator, follow these steps Go to https://developer.apple.com/download/all/?q=xcode%20beta Look for an iOS Simulator for Xcode-beta (e.g iOS 18.1 beta 6 Simulator Runtime) Download the .dmg file After downloading, open your terminal and run the command the following commands: a. sudo xcode-select -s /Applications/Xcode-beta.app b. xcodebuild -runFirstLaunch c. xcrun simctl runtime add "/Downloads/iOS_18.1_beta_6_Simulator_Runtime.dmg" d. xcodebuild -importPlatform "/Downloads/iOS_18.1_beta_6_Simulator_Runtime.dmg" Open your Xcode-beta app and you should see that your installation is successful. Note: I did this on my 2018 Macbook Pro. Also I used it while building a Flutter app for iOS See https://medium.com/@pouyahallaj/how-to-manually-download-and-install-ios-simulator-files-for-xcode-on-mac-b146923fd198 for more info. it was a helpful resource i found when fixing my own issue.