Hartley Charlton at MacRumors:
macOS 27 Golden Gate removes AFP support, ending Time Machine compatibility with Time Capsule after nearly two decades, but a community project from a Microsoft engineer offers a potential workaround for owners not yet ready to move on.
The original Time Capsule was announced way back in 2008, in the same Macworld keynote as the first MacBook Air. From Apple at the time:
Time Capsule combines an 802.11n base station with a server grade hard disk in one small package. Simply plug it in, then easily set up automatic wireless backup for every Mac® in your house to a single Time Capsule with just a few clicks. Time Capsule offers the benefits of a full-featured 802.11n Wi-Fi base station, and comes in two models: a 500 gigabyte model for just $299 and a 1 terabyte model for just $499.
“Bring Time Capsule home, plug it in, click a few buttons on your Macs and voila—all the Macs in your house are being backed up automatically, every hour of every day,” said Steve Jobs, Apple’s CEO. “With Time Capsule and Time Machine, all your irreplaceable photos, movies and documents are automatically protected and incredibly easy to retrieve if they are ever lost.”
The first version shared the same industrial design as the AirPort Extreme base station:

(Technically, it was slightly larger than the regular AirPort Extreme, but unless you had them side by side, most people wouldn’t notice.)
It did not take long for problems to start showing up, from kernel panics to dead power supplies.
It also did not take long before folks started cracking the things open and putting larger hard drives in them, which is a type of tinkering I truly miss in our modern age.
Over time, things settled down. In 2009, Apple updated the Time Capsule twice, ending the year with 1 TB and 2 TB models at the same $299 and $499 price points. Those updates also improved wireless performance for 802.11n clients through simultaneous dual-band and improved antennas.
In 2011, the Time Capsule was updated again, this time with 2 TB and 3 TB models at the same $299 and $499 prices.
In 2013, the entire AirPort line was overhauled, adopting a new form factor.

This time, the Time Capsule and AirPort Extreme looked identical at 3.85" x 3.85" x a somewhat unusual 6.6”. The new design was part of the move to 802.11ac, which Apple implemented with a total of six antennas inside.
2013 would prove to be the final update to these products. They sat for sale, unchanged, for five years. Then, the news came from Apple, to Rene Ritchie at iMore, who wrote:
Apple is ceasing production of its AirPort Express, AirPort Extreme, and AirPort Time Capsule Wi-Fi routers. I had a chance to speak to Apple briefly about the decision, and here’s the statement I was given:
“We’re discontinuing the Apple AirPort base station products. They will be available through Apple.com, Apple’s retail stores and Apple Authorized Resellers while supplies last.”
I understood the move at the time, but part of me still thinks it was a mistake for Apple to leave the Wi-Fi market right as mesh networking was becoming more common in the home. The AirPort’s ease of use would have been welcomed in the new landscape.
That aside, Apple’s cancellation of the hardware didn’t kill units in the field. I am sure there are folks who continue to run AirPort base stations today, but as Charlton wrote at MacRumors, the end has come for using a Time Capsule as a backup target. Notably, this move was announced a year ago.
The reason is that Apple is ending support for the Apple Filing Protocol. AFP can trace its roots back to System 6, which launched THIRTY EIGHT YEARS AGO. The more modern AFP that Apple is killing with Golden Gate was born with the advent of Mac OS X. For years, it was the protocol for sharing files between OS X machines, but it has since been superseded. Heck, it’s been 13 years since OS X Mavericks switched to SMB2 as its default file-sharing protocol.
Thankfully, you can still use Time Machine across a network. I have this set up for three MacBook users in my household, and it works well.
All of that said, the Time Caspule meeting its end isn’t surprising, even if it is a bit sad.