If you still use Time Machine to backup your Mac to an AirPort Time Capsule, you might want to hold off updating to macOS 27 Golden Gate. macOS 27 drops support AFP, the legacy file-sharing protocol that Time Capsule relies on for Time Machine backups. Backup now rely on the SMB protocol, meaning your discontinued Time Capsule hardware no longer meets the requirements of macOS 27.
Apple, back in the 2000s and 2010s, sold a lineup of WiFi routers called the AirPort. The lineup not only offered an AirPort Express and AirPort Extreme with the usual router features, it also offered an AirPort Time Capsule that also doubled as external storage, with the ability to back up Macs using Time Machine.
While Apple discontinued the AirPort lineup back in 2018, it has continued to offer AirPort Time Capsule backups.
The AirPort lineup went without an update for quite awhile before Apple’s announcement, with the AirPort Express receiving its last update in 2012, while the AirPort Extreme and Time Capsule both last received any update love in 2013.
Apple warned macOS users about the change back in June 2025, when macOS Tahoe began displaying a warning that Time Capsule backups would no longer work in the next macOS, so users have been warned.
If you wish to continue using Time Machines, you’ll need to find an alternate storage solution, like an external drive or a modern NAS.