I also encountered a problem today. sudo kextload /Library/Extensions/AppleFWAudio.kext Executing: /usr/bin/kmutil load -p /Library/Extensions/AppleFWAudio.kext Error Domain=KMErrorDomain Code=29 "Authenticating extension failed: Kext jjos.com.apple.driver.AppleFWAudio v270.19.2 in executable kext bundle jjos.com.apple.driver.AppleFWAudio at /private/var/db/KernelExtensionManagement/Staging/jjos.com.apple.driver.AppleFWAudio.3nHPxy/AppleFWAudio.kext: Authenticating extension failed: Bad code signature" UserInfo={NSLocalizedDescription=Authenticating extension failed: Kext jjos.com.apple.driver.AppleFWAudio v270.19.2 in executable kext bundle jjos.com.apple.driver.AppleFWAudio at /private/var/db/KernelExtensionManagement/Staging/jjos.com.apple.driver.AppleFWAudio.3nHPxy/AppleFWAudio.kext: