Final Cut Pro hangs while validating audio units

Found the solution. I had recently installed Screens 4. Uninstalled it, then uninstalled FCPX totally, reinstalled, and everything is now fine.

But yes, there is an AU Validation issue. Mine hung up on various different AudioUnits, including Apple's own SoundIsolation AU.

I really don't think it's specific AUs, it's something buggy in Ventura 13.3.1 AU Valitator system. FYI; Logic Pro X nor any other app I have that uses AUs has any issues at all. FCPX seems to just get more buggy with every macOS update.

Before following the below steps recommended by a Reddit user (credits to AyenneTeajay), I too had same problem on my MBP M2 Max. Even deletion of FCP preferences & re-installation of FCP didn't help. Later after moving all the Audio Components as specified in below steps, finally could launch the FCP. Later I have copied back all Components except the two that were reported as incompatible. In my case, the two plugin/components culprits were MConvulution EZ & MRecorder.

1. Go to your plug-ins folder (Macintosh HD/Library/Audio/Plug-Ins/Components
2. Copy all of the files and paste them somewhere else (you'll need to copy them back later)
3. Delete them from the plug-ins folder (the one from step 1)
4. Start Final Cut
5. If it opens, close it and start copying back the plug-ins in small bunches at once - say 10 at a time (or whatever comforting division you like), as after each paste, start Final Cut again to see if it works.
6. If Final Cut gets stuck again after some portion of the plug-ins is pasted, remove this portion and add the components one by one, as you start Final Cut after each paste so you can see which component causes the problem.
7. After isolating the wrong component, keep adding the rest of the plug-ins in bunches by 10 (or another comforting division) and keep checking them by opening Final Cut. Ideally, in the end, you will have it working with all the plug-ins pasted back into the original plug-ins folder (the one from step 1.)

I can understand your frustration but you probably don't need such drastic measures. Just rename /Library/Audio/Plug-Ins/Components to Components.ignore or whatever you'd like so FCP won't try to load them at launch. When you want to run Logic or another DAW, just rename it back to Components.

It seems this AU issue is due to something related to the macOS 13.3.1 update since that's when most people here say they encountered it so hopefully Apple will provide a fix to FCP or macOS soon.

i had similar until i deleted fcp preference files. Hold cmd + alt while launching fcp x app. It’ll ask if you want to delete prefs. Then it’ll rescan AUs. After that for me i was able to single out the “incompatible” plugins in fcp.

YMMV! But for me the only brand i had issues with in FCP was Izotope. Everything else, including waves, ik multimedia, arturia, slate, etc worked fine once id removed izotope AUs.

So... I swapped out the offending unit, only to have it hang on the very next one -- as though the problem is whatever unit it happens to hit as its 43rd. Grrr.

So I took a nuclear strike approach - went to Library > Audio and just renamed the Components folder. That way FCP didn't see any of them at all. Which is fine for my use case. And now I'm up and running.

Thanks for the tips above!

There have been some similar reports recently. Apparently some audio units cause trouble with FCP.

At the moment, the only way I know to go through this is to divide and conquer, to find which audio units are problematic, and keeping them out of the folder location when launching FCP.

You may be interested to read these other threads:

Final Cut Pro hangs on Audio Unit validat… - Apple Community

Re: Izotope plug ins stopping FCPX from working

Yes,I have same issue.

I've taken the plunge to update to Ventura (13.3) today, only to be disappointed with FCP X (10.6.5) problem hanging with validating audio units. I have over 1100 3rd party audio plugins, so it took a long time to separate invalid ones in order to get FCP X to even run without hanging. Best way is grouping alphabetically, and placing into a folder within the components folder in the Library.

Main issue now is that I have to manually keep moving plugins every time i switch between Logic Pro (10.7.7) and FCP X (10.6.5), as those plugins who do hang FCP X do not hang and validate perfectly in Logic Audio 10.7.7).

Currently FCP X does not seem to allow invalid plugins to be ignored or removed, as always there is no direct support to manage plugins as you can in Logic Pro.

I wish Apple would make FCP much more audio and audio mixing friendly. It leaves a lot to be desired.

I've read that force quitting FCPX and re-opening it several times will eventually make FCPX realize that there's a problematic plugin and disable it. I've tried it and it worked for me; I had two plugins that were incompatible and I eventually received the popup window that those two plugins were disabled. I did open the program with Option+Command too; not sure if it had an impact. Maybe try that a few times before diving into the plugins folder, which contains several hundreds in my case.

You may want to follow terryb's suggestion in another thread: temporarily rename the Components folder as something else, like Components.inactive; this will disable all components at once. It can serve as a workaround until this is fixed - hopefully in the next OS update.

Have you seen my solution just above your post?

Create a new volume on your boot drive with Disk Utility, install an earlier version of macOS on that and use it for FCP.

Once you have the installer the whole process takes less than half an hour and you will be able to use FCP and all your plugins exactly as before.

How to download macOS - Apple Support

If you’ve moved all components out, also try deleting preferences by holding down alt + cmd keys when you launch the fcp x app. It should come up with a prompt to delete prefs.

Removing "problematic" plug-ins is not an option because the problematic plugins basically = all plug-ins.

The issue is the AU Validator Tools are complete garbage, and when it crashes on something it breaks FCP. It stops Validating (using no CPU, just persisting as is in memory) and the user is stuck looking at a splash screen.

No matter how many plug-ins I uninstall, it chooses a different vendor's plug-ins to freeze on.

Uninstall Waves, Freezes on Native Instruments.

Uninstall Native Instruments, Freezes on iZotope.

Uninstall iZotope, Freezes on Arturia.

Uninstall Arturia, Freezes on Serato.

etc.

The only way to run this software - as far as I'm concerned - is to run it on a machine that has no Audio Units installed, as that's the only way you will avoid the AU Validator Tool breaking the application.

Third party plug-ins are fine. The fact that they run fine in multiple hosts in a range of formats is pretty indicative of that. The only outlier is Apple's software, particularly the AU Validator Tool that predictably crashes during plug-in validation and leaves the software in a perpetual unusable state.

The only fix, right now, is to avoid buying or using Final Cut Pro. Use Resolve Studio or Premiere Pro instead. In particular, a DAW or NLE that uses VST3 will completely avoid the issues with AU Validation by virtue of not requiring it.

Replacing Final Cut Pro with Resolve Studio and Logic Pro with Studio One or Cubase Pro = Problem-Free machine, because I don't have to deal with Apple's AU Validator Tools and just use the VST3 plug-ins.

Honestly, I'm probably going to just resell this machine and recoup as much of my losses as possible as the software renders it not very usable for the reason I purchased it. I could have just kept using my Windows machine, which has never given me these types of issues, and ended up a happier user without having wasted thousands of dollars.

No one from Apple engineering here. This is a user to user forum. Please use feedback to report your issue. You could try using FCP in a separate admin user on your system.

At what point in the Force Quit process did you launch FCP with Command+Option? (This deletes FCP's preferences.) In other words, did you Force Quit FCP several times, then launch FCP with Command+Option to delete preferences and then FCP opened telling you it was disabling some plugins?

My solution takes only a few minutes of your time as downloading the macOS and installing it is done automatically. Creating a new volume takes literally around a minute and the only other thing that takes any of your time is creating the new account etc. on the new volume . . . again only a few minutes.