The first best thing to do if you can is postpone the update as long as possible. If, however, you had made the update even past the official release like I did and ended up with a scenario where the app won't run and the emulator keeps downloading and reporting errors around the disk being full, here's what I did. I visited the download page on developer.apple.com (https://developer.apple.com/download/all/?q=Simulator%20Runtime) and downloaded the DMG file Then I went to follow the instructions on Installing additional simulator runtimes available at https://developer.apple.com/documentation/xcode/installing-additional-simulator-runtimes Now the emulator works and you can save days trying to install and re-install it via the Platforms section on XCode where if an error happens, you have to start downloading the runtime for the beginning every single time.