"Failed to load Audio Unit" errors on opening project, but plugins actually load OK

Question

I'm experiencing an issue where Logic Pro X will give an error saying "Failed to load Audio Unit" when loading a project, but when you actually click "Continue" and go on into the session the plugins are there and work fine - playback and bouncing all work fine, and the plugins were listed in the error dialogue all work fine.
Some notes on the error:
- it's happening on a range of different plugins on my system - ilok-protected plugins (Soundtoys, Slate among others), UAD plugins, and non-dongled plugins (Plugin Alliance stuff, among others)...
- seems that as a project is worked on over time, at some point the error starts to happen on a save, and then becomes apparent on the next reload... it also translates between systems - a couple projects where this is occurring were started in a different studio (where the error first showed up), and working on them at my studio the error is still apparent.
- also it seems like the error doesn't happen every time a project is loaded. If I'm launching Logic fresh and opening a project, the error will occur, but if I close and open another project and the come back to the first project again, the error won't show up on the first project anymore... but if I quit Logic and open that project again, it'll start happening again.
Has anyone else noticed this error?

Answer 1

Start Logic and hold the control key to disable the audio engine.
You should be able to load the project now, and disable the offending plugin. When done, turn the audio engine back on in the audio drivers preferences.