An error in the macOS recovery causes significant problems on ARM Macs: The attempt to reinstall the operating system on one of the Macs with Apple’s M1 chip currently fails with an error message, as several users report. After deleting the SSD and reloading macOS 11 Big Sur, the message appears that an error occurred while preparing the update, “The personalization of the software update has failed” – you should try again.
Restore from second Mac only
However, further attempts would result in the same error message, according to affected users. Normal startup of the Mac is no longer possible at this stage. As things stand, the only way out is to repair or restore the Mac’s firmware using DFU mode – similar to what is known from iPhones, but more cumbersome: The firmware restore requires a second Mac with at least macOS 10.15.6 Catalina and the Apple Configurator 2 tool, which can be downloaded free of charge from the Mac App Store.
To connect the two Macs, you also need a USB-C-to-USB-C cable or – for interaction with older Macs – a USB-A-to-USB-C cable. The cable must support the transmission of data and power, emphasizes Apple. According to the manufacturer, Thunderbolt 3 cables are not supported, but experience reports show that they still work.
The cable must be plugged into a specific port on the Mac to be restored, such as Apple notes in its instructions, which are currently only available in English. In order to put the M1-Mac into DFU mode (Device Firmware Upgrade), a specific key combination must also be pressed directly after switching on. If the procedure outlined by Apple fails, users can rely on a testimonial based on experience reports Refer to instructions from Mr. Macintosh. Recovery via DFU mode and a second Mac is nothing new, it also works on all Macs with Apple’s T2 security chip.
Users of the new M1 Macs – MacBook Air, MacBook Pro or Mac mini – should initially refrain from reinstalling the operating system, as far as possible, until Apple has created a way to do this again normally via macOS recovery.