I am having the same issue installing Beta 5 from a Beta 1 DTK. When I run it from the command line, I get the following error: Failed to download & prepare update: Error Domain=SUMacControllerError Code=7722 "[SUMacControllerErrorPreflightPrerequisiteCheckFailed=7722] Failed to perform PreflightPrerequisite operation: com.apple.MobileSoftwareUpdate.preflight.error(Preflight):12 | The base build is not compatible for this install method. > Current device configuration requires an alternate installer to perform the update.: [com.apple.MobileSoftwareUpdate.preflight.error(Preflight):12|Unknown Error Indication|]" UserInfo={SUMacControllerErrorIndicationsSummary=|Unknown Error Indication|, SUMacControllerErrorIndicationsMask=8, SUMacControllerErrorIndicationsDescription=-> Current device configuration requires an alternate installer to perform the update., NSUnderlyingError=0x14af06f00 {Error Domain=com.apple.MobileSoftwareUpdate.preflight.error Code=12 "The base build is not compatible for this install method." UserInfo={NSLocalizedDescription=The base build is not compatible for this install method., NSLocalizedFailureReason=The base build is not compatible for this install method., MSUPreflightAlternateInstallerRecommended=true}}, NSDebugDescription=[SUMacControllerErrorPreflightPrerequisiteCheckFailed=7722] Failed to perform PreflightPrerequisite operation: com.apple.MobileSoftwareUpdate.preflight.error(Preflight):12 | The base build is not compatible for this install method. > Current device configuration requires an alternate installer to perform the update.: [com.apple.MobileSoftwareUpdate.preflight.error(Preflight):12|Unknown Error Indication|], NSLocalizedDescription=Current device configuration and target is invalid for install in the current state. Please try again.}