Mixxx crashes upon startup after scanning iZotope AUs

[valtr1s]

Bug Description

Problem

I'm unable to run Mixxx because it crashes as soon as it tries to load iZotope "AUHook" plugins.

My hardware

M4 Pro Mac mini running macOS Sequoia 15.6

Here's everything I've found:

Upon launching, I see the Mixxx splash screen, but then I get a pop-up that says "One of the files this plug-in needs cannot be found, please reinstall or contact technical support for assistance." Clicking "OK" causes Mixxx to crash completely with a typical macOS "Problem Report" pop-up.

By running Mixxx from command line, I was able to narrow it down to iZotope Audio Units causing the issue. I tried quarantining each one, and I think it's specifically happening when it tries to load any AUs labeled "AUHook" at the end.

Here's what my terminal spits out right before it crashes:
2025-08-11 19:18:26.380 mixxx[98016:9634641] file:///Library/Audio/Plug-Ins/Components/iZNectar4Auto-LevelAUHook.component/ libc++abi: terminating zsh: abort /Applications/Mixxx.app/Contents/MacOS/mixxx

Quarantining all of my iZotope plugins mitigates the issue, and the program opens fine. I have no problems running iZotope AUs in DAWs or other programs, and they are legitimate copies licensed through Native Access.

Here's everything I've tried:

1. Uninstalling and reinstalling Mixxx, both through Homebrew and the pre-packaged binaries.
2. Uninstalling and reinstalling all of my iZotope plugins
3. Installing the 64-bit version, but it doesn't seem to run under Rosetta at all.
4. Launching under Safe Mode, but that doesn't disable plugin searching.
5. Looking through the config to see if there was any way to disable plugin searching upon start-up, but I couldn't find anything.

Here is my log:
mixxx.log

Please let me know if there is any other additional information you need from me :]
Thank you!

Version

2.5.2

OS

macOS Sequoia 15.6

[ronso0]

Maybe @fwcd has an idea how to debug this?

[timothybarraclough]

Hello, I'm new to mixxx and have been diagnosing something that sounds like it might be a similar issue. Specifically, none of the AUV3 audio units I have are able to be instantiated when Mixxx is launched – They all terminate prior to constructing the Parameter map, although this is silently ignored.

Once Mixxx has launched there are no issues with instantiating the AUV3 units – they just don't have any parameters exposed, which makes them unable to be controlled. @valtr1s – Are the Izotope Nectar plugins you're launching also AUv3? It's possible that attempting to instantiate them in process is crashing Mixxx if the plugin itself doesn't support being launched in-process.

[ronso0]

@valtr1s thanks for the log, but we need a backtrace to diagnose this properly. Please tryto create one with these instructions https://github.com/mixxxdj/mixxx/wiki/Creating-Backtraces#linux--mac-os-x-with-xcode-4x

CC @fwcd again, maybe you have an idea how to fix this / blacklist crashing AUs?

[leeronr]

@fwcd (?), @ronso0, I reproduced this crash in lldb and the stdout contained an extra line hinting at something to do with permissions/sandboxing in reading plist/preferences (?):

2026-02-12 09:32:14.867511+0200 mixxx[29019:2914769] [User Defaults] Couldn't read values in CFPrefsPlistSource<0x838bcdc00> (Domain: com.izotope.RX11REPAIRASSIST, User: kCFPreferencesAnyUser, ByHost: Yes, Container: (null), Contents Need Refresh: No): accessing preferences outside an application's container requires user-preference-read or file-read-data sandbox access

mixxx_crash_log.txt

mixxx_crash_backtrace.txt

M2 Pro, macOS 26.2, SIP off

[ronso0]

pinging @fwcd again, maybe you have an idea for a fix?

[xARSENICx]

@leeronr i would like for you to give my PR a try and see if the implemented solution works for you.

[leeronr]

@xARSENICx , sorry for delayed response. Built 2.5 post-PR. Haven't done extensive testing, but the AU-loading hurdle is cleared, all loads, and basic functionality works. I have little-to-no experience with mixxx—was/am looking forward to playing around and trying it out—so I don't know how to test the actual AU functionality.

Thanks for the fix; keep up the great work!

[ronso0]

Fixed by #16106