制作系统盘失败

Error: Error Domain=NSCocoaErrorDomain Code=512 "未能将“InstallESD.dmg”拷贝到“SharedSupport”。" UserInfo={NSSourceFilePathErrorKey=/Applications/Install macOS Mojave.app/Contents/SharedSupport/InstallESD.dmg, NSUserStringVariant=(

    Copy

), NSDestinationFilePath=/Volumes/UNTITLED/Install macOS Mojave.app/Contents/SharedSupport/InstallESD.dmg, NSFilePath=/Applications/Install macOS Mojave.app/Contents/SharedSupport/InstallESD.dmg, NSUnderlyingError=0x7f90ea3a2e40 {Error Domain=NSPOSIXErrorDomain Code=5 "Input/output error"}}The copy of the installer app failed.

每次进展到70%，就会失败，是什么问题呢？我是MacBookpro15款，不小心升级最新感觉很难受，想退回mojave