Apple kills kernel extensions: Dropbox re-architects sync onto File Provider

For years, Dropbox's online-only and Smart Sync features on the Mac depended on a kernel extension (kext) that let placeholder files behave like real files to every app on the system. Apple had been deprecating kexts since 2019 in favor of user-space frameworks, granting Dropbox and Microsoft temporary signing exemptions while they re-engineered. With macOS 12.3 (Monterey) in 2022, Apple removed the system support those kexts relied on, and Dropbox had to migrate to Apple's File Provider framework.

The transition changed user- and developer-visible behavior. Apple acknowledged that after updating to macOS 12.3, users could temporarily hit problems opening online-only files in some third-party apps. Under File Provider, the Dropbox folder moved into ~/Library/CloudStorage, so previously linked files in third-party apps had to be relinked; sync performance came under macOS's control (and could throttle on low battery or heat); LAN sync was disabled; macOS package files such as .pages and .numbers began behaving as regular files; and certain libraries (Photos, Final Cut Pro, Adobe InDesign lock files) could no longer sync.

The re-architecture was driven by Apple, not Dropbox, but it forced a fundamental rewrite of Dropbox's most distinctive Mac feature and disrupted the integrations and workflows built around the old behavior.