I am trying to migrate an Audio Unit host based on the AUv2 C API to the newer AUv3 API. While the migration itself was relatively straightforward (in terms of getting it to compile), the actual rendering fails at run-time with error -10876 aka. kAudioUnitErr_NoConnection.
The app does not use AUGraph or AVAudioEngine, perhaps that is an issue? Since the AUv3 and the AUv2 API are bridged in both directions and the rendering works fine with the v2 API, I would expect there to be some way to make it work via the v3 API though.
Perhaps someone has an idea why (or under which circumstances) the render block throws this error?
For context, the app is Mixxx, an open-source DJing application, and here is the full diff between my AUv2 -> v3 migration: https://github.com/fwcd/mixxx/pull/5/files