Updated August 19: Apple has released iOS 17.6.1 again with a new build number (21G101), almost two weeks after its initial release on August 7. It is not clear what has changed or why Apple issued a new build of this version.
Advanced Data Protection is a feature introduced in iOS 16.2 that brought end-to-end encryption to nearly all iCloud features, seriously raising the privacy and security of Apple’s cloud services. Apparently, there’s a serious bug with it in iOS 17.6, because Apple has just released an iOS/iPadOS 17.6.1 update that specifically addresses a problem with it.
The release notes simply state:
This update includes important bug fixes and addresses an issue that prevents enabling or disabling Advanced Data Protection.
There are no explanations about what other bugs may be fixed, but if Apple is calling out the Advanced Data Protection issue, that’s easily the most significant one. Apple also released iOS/iPadOS 16.7.10, macOS Sonoma 14.6.1, and macOS Ventura 13.6.9 with the same fix.
Apple’s security updates page says “This update has no published CVE entries.” That does not mean there are no security patches in the update, only that any fixes that exist were for issues not published in the Common Vulnerabilities and Exposures database.
If you are running iOS 17.6, you should update to this version immediately.