iMac m4, Sequoia 15.11. When I use send to Compressor from FCP the project hangs with a message Incompatible Audio Units found. Apple:AULowShelfFilter and AUMultibandCompressor. I can't find them in any of the libraries. Doesn't happen if I use Share in FCP. Here is the message. If I click on OK, it works one time. Apple knows where these are, but I don't. Irritating for sure. Come on Apple!
iMac 24″, macOS 15.1
When you moved apps to your new Mac it may have copied over AU cache files from a prior MacOS version. If so that's an example of why it's best to perform a clean install of apps and plugins from scratch on a new machine.
Use Terminal’s auval -a | grep -i "LowShelfFilter\|MultibandCompressor" to confirm exactly where the system is loading these from.
On my machine running FCP 11.0, Compressor 4.9 and MacOS 15.2, it gives this output. If yours does not say this, post what it returns:
aufx lshf appl - Apple: AULowShelfFilter
aufx mcmp appl - Apple: AUMultibandCompressor
In Finder go to ~/Library/Caches/AudioUnitCache/ and remove any *.cache files inside.
Reboot your Mac, which restarts the audio daemon process.
Launch FCP and Compressor. On the first startup after clearing caches, the system re-validates the Audio Units. Check if the error persists.
If it still happens, use these terminal commands to individually validate those two MacOS AU plugins. Save the output and inspect for any validation or other errors:
auval -v aufx lshf appl
auval -v aufx mcmp appl
However, the above MacOS commands are generic. The FCP/Compressor validation checks run by the "Flexo" private framework are much more detailed. That could potentially include concurrency constraints, channel format support, sample-rate compatibility, or specific flags that are unique to FCP or Motion. That is really good because a buggy or wrong-version MacOS system plugin could destabilize FCP or Compressor. OTOH it's possible auval could pass yet the Flexo AU validation checks could fail. So the above are just attempts to find the problem source, they are not guarantees.
Using Finder's "Go to Folder" menu, go here: ~/Library/Caches/AudioUnitCache/Logs/
There will be one or more AU validation log files there with a .plist file extension. Please compress those and upload to a file sharing site I can access.
Also use the below terminal command to search your entire system for any other AU validation log files. If any others are found, upload those also.
sudo find / -name "*AUScan*" 2>/dev/null
Once those commands finish, run this one which searches your entire machine for any AU caches that might have been brought over by the migration from the old Mac:
sudo find / -name "*audiounits*" 2>/dev/null
If the above finds anything, compress and upload those so I can examine them.
After doing the above, save the full output of the terminal screen, inc'l scrollback buffer: do CMD+A, CMD+C, then paste that into a plain text TextEdit document, and also upload that. The purpose is so I can double-check all the pathnames of the listed files.
This was messing me up, too, but in Motion and Compressor. Motion 5.9, MBP M1 Max, Sequoia 15.3
That "Incompatible Audio Units Found" pop up is hard to find--it's not a window, and it appears behind your active window, so you have to drag your active window out of the way to see it. Clicking "Do not warm me again" and then OK seems to have worked for me.
Compressor and Motion both were failing to export anything at all. Please note, I had to click "Do not warn me again" multiple times--In Motion, in Compressor twice I think. But it's finally transcoding an export for me now
Glad that worked for you. Perhaps those AU plugins are being deprecated. Your FCP and Compressor are updated to the latest versions?
You should send this to FCP Feedback. Final Cut Pro->Provide Final Cut Pro Feedback... or use this link Feedback - Final Cut Pro - Apple
Those AU plugins appear to be wrappers for classes in the MacOS Audio Toolbox framework: Audio Toolbox | Apple Developer Documentation
Flexo is the main FCP private framework and that is what validates the AU plugins and calls them. I believe many of the private frameworks such as Flexo are shared between FCP, Compressor and Motion.
There are many validation checks in Flexo to ensure the AU plugin is the right version and has the right characteristics such as channel config.
We definitely need to know the specific version of FCP and Compressor he's running.
I think there are similarly-named plugins for Logic Pro. There is a procedure to make those effects visible to FCP. If FCP and Compressor were updated but Logic was not updated, yet he's using the Logic version of those two plugins, that might cause it.
Or it could be as simple as FCP was updated and Compressor was not.
I can see that Flexo is working each time I try compressor and leaves a file behind -- The path to it is below. Not helpful for me, but maybe a clue for an expert as to where these faulty plugins are hiding.
I believe I have the latest versions. Show up when I start the programs--FCP 11.0 and Compressor 4.9. I just ran these two and got the same message. These AU plugins are hiding somewhere on my new Mac. I have never used Logic. As I moved apps to my new Mac it may be an earlier version was hanging around on a backup disk. Obvious Flexo is finding the plugins it doesn't like, but I haven't found them.
Thanks for these suggestions. I followed through the above instructions. I got the same responses that you mentioned above. I cleared the cache, the error remained. I did the validation of the two plugins and no errors were detected. So no progress. While I did a clean install of apps, I know that I had a backup of my previous internal disk running, when I opened the newly downloaded FCP and when I opened compressor, it used an old version found on by backup disk. In the latest tests, only the internal hard drive is connected, so the problem is definitely in there somewhere. So I guess Flexo AU is still finding this problem somewhere on the internal hard drive of the new MAC.
I ran the various Sudo finds suggested. I did find audio containers in GarageBand. So I will try to look there. Here is the whole terminal text from the search. Not sure how to send it through a data sharing program, but it is short. (thanks) Last login: Mon Jan 27 20:14:55 on console
claudelyneis@Claudes-iMac ~ % sudo find / -name "*audiounits*" 2>/dev/
zsh: is a directory: /dev/
claudelyneis@Claudes-iMac ~ % sudo find / -name "*audiounits*" 2>/dev/null
Password:
claudelyneis@Claudes-iMac ~ % auval -a | grep -i "LowShelfFilter\|MultibandCompressor"
aufx lshf appl - Apple: AULowShelfFilter
aufx mcmp appl - Apple: AUMultibandCompressor
claudelyneis@Claudes-iMac ~ % sudo find / -name "*AUScan*" 2>/dev/null
Password:
/System/Volumes/Data/Users/claudelyneis/Library/Containers/com.apple.garageband10/Data/Library/Caches/AudioUnitCache/Logs/AUScan01-01-2025_10-00-38.plist
/Users/claudelyneis/Library/Containers/com.apple.garageband10/Data/Library/Caches/AudioUnitCache/Logs/AUScan01-01-2025_10-00-38.plist
claudelyneis@Claudes-iMac ~ % sudo find / -name "*audiounits*" 2>/dev/null
claudelyneis@Claudes-iMac ~ %
(1-27-2025). I found the two containers above and their caches. These were associated with GarageBand. I got rid of these and for good measure I got rid of GarageBand. I restarted and tried to compress a video file from FCP using Compressor. Same old message came up, but only once or twice before the Compressor completed the task. I restarted and ran the sudo finds listed above. This time they found nothing. Obviously Flexo thinks differently. So I want to thank all those who made suggestions, but I am quitting this hunt. I suspect my mistake was during the configuration of my new Mac after downloading a fresh copy of FCP, I ran it with a backup disk from the old Mac connected and it found an older version of Compressor or maybe GarageBand etc. So I will just go with a workaround of using Share, or wait for the Flexo window to come up once or twice and clear it. I don't use FCP and Compressor daily, so it is just an irritation not a overriding issue.
Does the error happen if you create a Compressor Share Destination and then Share using this instead of Send to Compressor? Create share destinations in Final Cut Pro for Mac - Apple Support
The error does not show up when using a Share Destination, so that is a good workaround. Thanks.
Claude, thanks for noticing that. Please send me that flexo file from today and a few previous ones. Compress those before uploading to a file sharing site.
Excellent point. I went through the same problem when the warning window was hidden.
Final Cut Pro Compressor stalls Incompatible Audio Units found
