The error message "Registering simulator runtime with CoreSimulator failed" encountered during the download of the iOS 17.0 SDK in Xcode 15.0 is typically attributed to insufficient available disk space. In order to successfully complete the download and registration process, it is necessary to have approximately 40 GB of free storage space at your disposal. Although the actual installation of the SDK consumes an estimated 9 to 12 GB of storage, a preliminary requirement of around 40 GB of free storage is imposed prior to initiating the installation process. Ensuring that this requisite disk space is available before proceeding will likely resolve the encountered issue.